ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Electron microscopy  (478)
  • ASTROPHYSICS
  • Cell & Developmental Biology
  • Chemistry
  • Inorganic Chemistry
  • Polymer and Materials Science
  • Springer  (493)
  • 1990-1994  (100)
  • 1970-1974  (393)
Collection
Keywords
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 6 (1991), S. 363-366 
    ISSN: 1435-604X
    Keywords: Laser vascular welding ; Tissue fusion ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The central problem in microsurgery is the reconstruction of small vessels. The long operating time, foreign body granuloma formation around the suture material as well as aneurysmal alterations of the vessel wall after conventional suture technique make the search for alternatives indispensable. Some of these disadvantages can be avoided as demonstrated by our animal experiments and histological examinations in laser-assisted anastomosing. The aim of this study is to show these aspects in connection with laser application and compare them with conventional suture techniques.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1572-8773
    Keywords: Ferritin ; Thalassemia ; Ferrihydrite ; Crystallinity ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The cores of ferritins isolated from different organs of human subjects withβ-thalassemia/hemoglobin E (β-thal/HbE) disease have different size distributions and crystallinities depending on the source organ. These patients have not been treated by hypertransfusion regimen or iron chelation therapy.β-Thal/HbE spleens and livers yield ferritin cores which are less crystalline than those isolated from normal spleens and livers, reflecting the more rapid deposition of iron in the diseased state. Ferritins isolated from the hearts and pancreases ofβ-thal/HbE subjects were found to have larger, more crystalline cores than those from theβ-thal/HbE livers and spleens, possibly as a consequence of the role of the heart and pancreas as long-term iron deposition sites in this iron overload pathology.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 10 (1972), S. 82-90 
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Precipitation ; Kinetics ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La cinétique de la formation et de la transformation des précipités de phosphate de calcium, obtenus en mélangeant de volumes égaux de solutions à 6×10−3 M de calcium total et/ou phosphate total est étudiée à 25°C. Les solutions de phosphate sont préajustées à un pH de 7.4. Les changements de pH et de turbidité des solutions sont suivis simultanément en fonction du temps. Les précipités sont isolés à des intervalles de temps variables et caractérisés par diverses méthodes physico-chimiques. Initialement un précipité avec un rapport molaire Ca/P de 1.5, amorphe aux rayons X et en diffraction électronique, est formé. Le spectre IR indique la présence de PO 4 3− et de HPO 4 2− . Après une période métastable, on observe la précipitation d'un matériel cristallin dans ou sur la phase amorphe. Vingt quatre heures après préparation de l'échantillon les précipités présentent surtout les caractères du phosphate octocalcique.
    Abstract: Zusammenfassung Die Kinetik der Bildung und Transformation von Calciumphosphat-Niederschlägen wurde bei 25°C untersucht. Es wurden dazu gleiche Volumen von Lösungen gemischt, bei einer Konzentration von 6×10−3M totales Calcium und/oder totales Phosphat. Die Phosphatlösungen wurden zuerst auf pH 7,4 eingestellt. Veränderungen des pH und Trübung der Lösungen wurden gleichzeitig als eine Funktion der Zeit aufgezeichnet. Niederschläge wurden in verschiedenen Zeitintervallen isoliert und mit verschiedenen physiko-chemischen Methoden charakterisiert. Am Anfang wurde ein Niederschlag mit einem molaren Ca/P-Verhältnis von 1,5, im Röntgenbild und in der Elektronendiffraktion amorph, gebildet. Infrarotspektren deuteten die Anwesenheit von PO 4 3− - und HPO 4 2− -Ionen an. Nach einer metastabilen Periode erfolgte ein Niederschlag aus kristallinem Material innerhalb oder auf der amorphen Substanz. 24 Std nach der Herstellung der Proben zeigten die Niederschläge in der Hauptsache die Charakteristiken von Octocalciumphosphat.
    Notes: Abstract The kinetics of the formation and transformation of calcium phosphate precipitates obtained by mixing equal volumes of solutions, 6×10−3 M in total calcium and/or total phosphate was investigated at 25°. The phosphate solutions were preadjusted to pH 7.4. Changes of the pH and turbidity of the solutions were followed simultaneously as a function of time. Precipitates were isolated at various time intervals and characterized by different physicochemical methods. Initially a precipitate with a molar Ca/P ratio of 1.5, amorphous to X-ray and electron diffraction was formed. IR spectra indicated the presence of PO 4 3− and HPO 4 2− ions. After a period of metastability, precipitation of a crystalline material within or upon the amorphous matter occurred. Twenty four hours after sample preparation the precipitates showed mainly the characteristics of octacalcium phosphate.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 145-152 
    ISSN: 1432-0827
    Keywords: EHDP ; Bone ; Chemistry ; Serum ; Rabbits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) on bone and serum chemistry were investigated in adult rabbits. EHDP was administered by subcutaneous injection at doses of 0.25, 2.5 and 10 mg/kg body weight/day for of 28 days. Blood samples were obtained weekly from each rabbit and serum levels of total calcium, ionized calcium, inorganic phosphate and alkaline phosphatase were determined. At the end of the treatment period all rabbits were sacrificed and the tibiae removed for chemical analysis and histological evaluation. The effect of EHDP administration on serum chemistry was both dose- and time-related. The highest of the three doses, 10 mg/kg/day, resulted in a time-related decrease in total serum calcium. This dose also caused a rapid but transient reduction in serum ionized calcium. The effect of EHDP on serum inorganic phosphate was biphasic. Administration of 2.5 mg/kg/day resulted in a time-related elevation in this parameter, whereas the 10 mg/kg/day dose resulted in a time-related hypophosphatemic response. There were no significant drug-related changes in tibial fat-free dry weight, ash weight, total calcium or total phosphorus values. However, administration of 2.5 and 10 mg/kg/day EHDP resulted in increased osteoid tissue as measured histologically. These results are compared with data from other EHDP studies, and discussed in relation to the maturity and growth-state of the experimental animals.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-2285
    Keywords: Picea abies (L.) Karst ; Freezing injury ; Acid rain ; Carbohydrate histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The cellular structures of acid rain-irrigated needles of several provenances of Norway spruce (Picea abies L. Karst) seedlings were studied after winter experimental freezing. Frost injuries and recovery were characterized by visual damage scoring and classification of mesophyll cell alterations, also using histochemical methods for carbohydrate fluorescent staining. The treatment with-30° C during the late dormancy period was sufficient to cause significant injuries and intracellular degradation in the tissues of the green needles. The most affected seedlings in terms of visual injury scoring were found among those treated with clean water or at pH 3, while freezing injury, defined as an occlusion of phenolic substances in the central vacuole of the mesophyll cells, was most abundant in the needles from spruces irrigated either with clean water or at pH 4 or pH 3. Electron microscopy revealed the details of the injury, e. g. thinning out of the cytoplasm and chloroplast stroma, darkening of the chloroplasts and eventually swelling of the chloroplasts and protoplast. PAS and ConA reactions in the needle tissue revealed intense starch accumulation in the mesophyll and transfusion tissues as early as in March, with a tendency to increase, especially in the untreated needles during the recovery period. Plasma membrane disturbances were indicated by histochemical identification of callose deposits in the mesophyll cell walls, these being most abundant in the acid rain-treated needles. All these findings suggest that freezing at −30° C was more deleterious to the seedlings pretreated with acid or clean water than to those not given additional irrigation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Trees 8 (1993), S. 23-30 
    ISSN: 1432-2285
    Keywords: Wound responses ; Hardwoods ; Xylem parenchyma ; Suberization ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wound responses of xylem parenchyma by suberization were investigated in some hardwoods by light and electron microscopy. Suberized ray and axial parenchyma cells form a distinct boundary around the wound in all investigated species. Vessels and fibres within and close behind the suberized area appeared more or less occluded; vessels in Fagus, Quercus, and Populus contained suberized tyloses, those in Betula and Tilia contained amorphous and fibrillar deposits. A common mechanism for suberin deposition in the parenchyma cells became evident. Cisternae of the endoplasmic reticulum were apparently involved in suberization. Suberin compounds are extruded by cytoplasmic vesicles, which fused with the plasma membrane, in order to release their content. The suberin layer exhibited the typical lamellated structure; cytoplasmic continuity between suberized cells by plasmodesmata was maintained through the suberin layer. Fagus revealed the most intense suberized area as compared with the other species. Within the reaction zone of Fagus and Quercus, some individual ray and axial parenchyma cells exhibited a subdivision into 2 or 3 compartments prior to suberization. Subdivision was achieved by the formation of a primary wall-like layer. Subsequently, the compartments became individually suberized. Wounding during winter did not induce suberization. Also, samples wounded and kept under water during the vegetation period showed no response. The role of suberization in the effectivity of wound-associated compartmentalization is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1573-0832
    Keywords: Microsporon audouinii ; Pyrrolnitrin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Scanning and transmission electron microscopy showed that a ceiling quantity (1.56 mcg) of antifungal antibiotic Pyrrolnitrin caused heavy damage to dermathophyteMicrosporon audouinii Gruby CBS 313-54in vitro. Suitable preparation technique made it clear that the changes involved consisted of hyphal collapse on the edge of the culture, with loss of euplasmic organelles identity and cell autolysis. The cell wall, however, was apparently undamaged. These findings fit in with the suggestion that the mode of action of the antibiotic leads to generalised lipoproteic membranes damage. They must, however, be considered as representing the result of the terminal phase of cell distress.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Mycopathologia 121 (1993), S. 143-147 
    ISSN: 1573-0832
    Keywords: Electron microscopy ; Farmer's lung ; Saccharopolyspora rectivirgula ; Thermoactinomyces vulgaris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The fine structure ofThermoactinomyces vulgaris andSaccharopolyspora rectivirgula is described by transmission electron microscopy. These two bacteria are the most common microbes causing farmer's lung. The fine structure of hyphae, germination of endospores and the details of conidial wall layers ofT. vulgaris, as well as the fine structure of septate hypha and globose, polygonal conidia ofS. rectivirgula are described. The conidial wall ofT. vulgaris consisted of an inner multilayered spore coat, intermediate spore coat and outer spore coat. The findings are important for the investigations to find fragments of these bacteria in the lungs of exposed patients and experimental animals.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 93-107 
    ISSN: 1432-0827
    Keywords: Dentinogenesis ; Globules ; Pyrophosphatase ; Calcification ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Three-day-old rats were fixed by perfusion with glutaraldehyde and thin slices were cut of the first molar germs. The slices were treated with EDTA and “activated” with buffered solutions containing Mg2+, Ca2+ or Zn2+. Incubation was carried out in buffered solutions (pH 8.5) containing inorganic pyrophosphate and Pb2+. In the Mg2+-activated specimens incubation products were localized to the plasma membranes in the stratum intermedium and the subodontoblastic area. Lead deposits were found on the periphery of the dentinal globules. Incubation products were more randomly distributed in Ca2+-activated specimens whereas those activated with Zn2+ displayed a deposition of lead precipitates mainly corresponding to that seen after activation with Mg2+. The findings are discussed in reference to the localization of alkaline phosphatase in the dentin-producing tissues and it is proposed that the results are indicative of the presence of an inorganic pyrophosphatase in these tissues.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 14 (1974), S. 3-14 
    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Mineral ; Phase ; Chemistry ; Synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des diagrammes de phase d'équilibre ont été déterminés pour le système CaO-P2O5-H2O en utilisant des techniques de synthèse hydrothermique au cours de variatio nsde température allant de 300–600° et 2 Kb H2O de pression. De l'hydroxyapatite bien cristallisé a été synthétisé et caractérisé. De faibles variations de paramètres de la maille cristalline, liées à la température de synthèse et composition globale du matériel initial, ont été déterminées. Des conditions chimiques précises sont nécessaires pour obtenir de l'apatite, en tant que seule phase solide en équilibre dans la solution. Les résultats de diagramme de phase d'équilibre sont comparés avec ceux obtenus dans des milieux synthétiques.
    Abstract: Zusammenfassung Es wurden Gleichgewichts-Phasendiagramme für das System CaO-P2O5-H2O bestimmt, indem hydrothermale Synthese-Techniken im Temperaturbereich von 300–600° und bei einem Druck von 2 Kb H2O verwendet wurden. Es wurde gut-kristallisiertes Hydroxyapatit erzeugt und charakterisiert. Es wurden geringe Unterschiede in den Parametern der Zelleinheiten festgestellt, welche von der angewandten Temperatur und der Zusammensetzung des Startmaterials abhingen. Es waren genaue chemische Bedingungen nötig, um Apatit als die einzige feste Phase im Gleichgewicht mit der Lösung zu erhalten. Die Resultate der Gleichgewichts-Phasendiagramme werden mit früheren Untersuchungen mit der Synthesetechnik verglichen.
    Notes: Abstract Equilibrium phase diagrams have been determined for the system CaO-P2O5-H2 using hydrothermal synthesis techniques in the temperature range 300–600° and 2 Kb H2O pressure. Well-crystallized hydroxyapatite has been produced and characterized. Small variations in unit cell parameters dependent on temperature of synthesis and bulk composition of the starting materials have been determined. Precise chemical conditions were required to obtain apatite as the only solid phase in equilibrium with solution. Equilibrium phase diagram results are compared with previous synthetic investigations.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 7 (1971), S. 150-162 
    ISSN: 1432-0827
    Keywords: Uranium ; Bone ; Distribution ; Fission ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une concentration moyenne de 2.4×10−8 g U/g de cendre a été obtenue à partir de l'os humain normal. La microdistribution de l'uranium dans l'os indique que cet élément est surtout limité à surface de l'endoste et, en particulier, aux surfaces de l'os lamellaire et aux parois des canaux de Havers, ouverts dans l'os corticol. Cette répartition suggère que l'uranium se présente sous une forme chimique impropre à son incorporation dans l'apatite osseux: il ne semble donc pas exister une distribution diffuse significative de l'uranium dans l'os.
    Abstract: Zusammenfassung Eine mittlere Konzentration von 2,4×10−8 g Uran/g Asche wurde in normalen menschlichen Knochen gefunden. Die Feinverteilung von Uran im Knochen zeigt, daß dieses Element hauptsächlich an der endostalen Oberfläche vorkommt, insbesondere an der Oberfläche des trabeculären Knochens und an den Wänden der offenen Haversschen Kanäle im kortikalen Knochen. Diese Verteilung läßt vermuten, daß Uran in einer chemischen Form vorliegt, welche sich für den Einbau in das Knochenapatit nicht eignet. Daraus folgt, daß keine signifikante diffuse Verteilung des Urans innerhalb des Knochens vorliegt.
    Notes: Abstract A mean concentration of 2.4×10−8 g U/g ash has been obtained for normal human bone The microdistribution of uranium in bone indicates that this element is mainly restricted to endosteal surfaces; in particular the surfaces of trabecular bone and the walls of open Haversian canals in cortical bone. This distribution suggests that uranium is present in a chemical form that is not acceptable for incorporation into bone apatite and consequently there does not appear to be a significant diffuse distribution of uranium throughout bone.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    ISSN: 1432-0827
    Keywords: Morphology ; Glycosaminoglycans ; Cartilage ; Chemistry ; Audioradiography ; Healing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une perte de substance ostéo-cartilagineuse, de taille limitée et identique, est réalisée chez le lapin adulte et la cicatrisation est étudiée histologiquement et par autoradiographie après marquagein vitro au35S-sulfate. Une analyse microchimique est pratiquée pour le contenu et la composition en glycosaminoglycanes. 1. Entre la première semaine et la 4ème et 8ème semaine, un tissu conjonctif non-métachromatique se différencie en un cartilage métachromatique et la quantité de sulfate de chondroitine augmente de façon significative aux dépens des glycoprotéines. 2. Jusqu'à la 4ème semaine, la perte de substance est surtout comblée par de l'os néoformé: après cette période, la région est comblée au delà de la limite de la surface articulaire. 3. Le cartilage hyalin, ressemblant morphologiquement, autoradiographiquement et chimiquement au cartilage articulaire, en ce qui concerne la distribution en glycosaminoglycanes, constitute la surface articulaire de la perte de substance comblée dans un tiers des cas après 8 semaines. Le cartilage hyalin s'observe surtout dans les régions où de l'os néoformé a comblé la cavité médullaire. 4. Dans les deux tiers des cas, après 8 semaines, les surfaces articulaires des zones comblées comportent, non seulement du cartilage, mais aussi du tissu fibreux se formant essentiellement sur les parties latérales et dans les régions, où la cavité médullaire, fliant face, à la surface articulaire, n'a pas été comblée par du tissue osseux. La fraction glycoprotéique augmente par rapport à la fraction chondroitine sulfate. 5. Dans la majorité des cas, après 20 semaines, le cartilage néoformé subit des phénomènes dégénératifs, qui se traduisent par une diminution en chondroitine sulfate.
    Abstract: Zusammenfassung Bei ausgewachsenen Kaninchen wurde ein begrenzter, standardisierter, osteochondraler Defekt hervorgerufen, und das regenerierte Gewebe wurde histologisch und autoradiographisch durch Markierung in vitro mit35S-Sulfat und durch mikrochemische Bestimmung des Gehaltes und der Zusammensetzung der Glykosaminglykane untersucht. Die wichtigsten Befunde waren: 1. Zwischen 1 und 4–8 Wochen veränderte sich nichtmetachromatisches Bindegewebe zu metachromatisch gefärbtem Knorpel, und der Anteil an Chondroitin-Sulfat nahm auf Kosten der Glykoproteine signifikant zu. 2. Bis zu 4 Wochen war der Hauptteil des defekten Gebietes mit neugebildetem Knochen gefüllt; nach dieser Zeit lag dieser Bezirk oberhalb der Verknöcherungsgrenze in Richtung der Gelenkoberfläche. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 4. Nach 8 Wochen bestanden Teile der Gelenkoberfläche des Defektes in zwei Dritteln der Fälle nicht nur aus Knorpel, sondern auch aus fibrösem Gewebe, welches vor allem in den seitlichen Teilen des Defektes und an Stellen vorlag, wo die Markhöhle gegenüber der Gelenkoberfläche nicht mit Knochengewebe verschlossen worden war. Die Glykoproteinfraktion nahm im Vergleich zur Chondroitin-Sulfatfraktion zu. 5. Nach 20 Wochen zeigten sich in den meisten Fällen bei neugebildetem Knorpel degenerative Veränderungen, welche durch eine gewisse Abnahme des Chondroitin-Sulfats wiedergegeben wurden.
    Notes: Abstract A limited, standardized osteochondral defect was created in adult rabbits and the regenerated tissue was examined histologically and autoradiographically after labellingin vitro with35S-sulphate, and microchemically for its content and composition of glycosaminoglycans. The principal findings were: 1. Between 1 week and 4 to 8 weeks, non-metachromatic connective tissue differentiated to metachromatically stained cartilage, and the proportion of the chondroitin sulphate increased significantly at the expense of the glycoproteins. 2. Up to 4 weeks, the major part of the defect area was filled with newly formed bone; after this time, the area lay above the level of the “tidemark”, towards the articular surface. 3. Hyaline cartilage with morphological, autoradiographic and chemical resemblance to the articular cartilage in terms of the distribution of glycosaminoglycans constituted the articular surface of the defect area in one-third of the cases at observation times after 8 weeks. Hyaline cartilage was observed mainly in areas where newly formed bone had closed the medullary cavity. 4. In two-thirds of the cases, after 8 weeks, parts of the articular surface of the defect consisted not only of cartilage but also of fibrous tissue, occurring mainly in the lateral parts of the defect and in areas where the medullary cavity facing the articular surface had not been sealed by bone tissue. The glycoprotein fraction increased relative to the chondroitin sulphate fraction. 5. In most cases after 20 weeks, newly-formed cartilage underwent degenerative changes, which were reflected in some reduction of the chondroitin sulphate.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 8 (1971), S. 165-171 
    ISSN: 1432-0827
    Keywords: Bone ; Ceramic ; Tetracycline ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un implant céramique non poreux est testé au niveau du fémur de rat en ce qui concerne son adhésivité à l'os. Un certain nombre de techniques morphologiques sont utilisées pour examiner le rapport entre l'implant et l'os néoformé. La microscopie électronique par transmission et la microscopie par fluorescence après marquage à la tétracycline ont donné les meilleurs résultats. Un rapport étroit entre l'os minéralisé et la céramique a été noté en microscopie électronique. Par marquage à la tétracycline, il semble que l'implant puisse stimuler la formation osseuse.
    Abstract: Zusammenfassung Ein unporöses keramisches Implantat in Rattenfemora wurde auf seine Fähigkeit geprüft, sich mit Knochen zu binden. Eine Anzahl morphologischer Techniken wurde verwendet, um die Beziehung zwischen den Oberflächen von Implantat und neuem Knochen zu untersuchen. Transmissions-Elektronenmikroskopie und Fluoreszenzmikroskopie nach Tetracyclinmarkierung waren die erfolgreichsten Techniken. Eine enge Beziehung zwischen mineralisiertem Knochen und dem Keramikimplantat konnte mit der Transmissions-Elektronenmikroskopie nachgewiesen werden. Das Aussehen der Tetracyclinmarkierung im keramischen Implantat deutet darauf hin, daß dieses wahrscheinlich die Fähighkeit hat, Knochenbildung zu erhöhen.
    Notes: Abstract A nonporous ceramic implant in rat femora was evaluated as to its ability to bond to bone. A number of morphologic techniques were utilized to examine the interfacial relationship of the implant to new bone. Transmission electron microscopy and fluorescence microscopy after tetracycline labelling were the most successful techniques. An intimate relationship between mineralized bone and the ceramic was demonstrated by transmission electron microscopy. The appearance of tetracycline labelling at the ceramic interface indicates that the implant may have capacity to enhance bone formation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 8 (1971), S. 228-236 
    ISSN: 1432-0827
    Keywords: Skin ; Calcinosis ; Keratin ; Chemistry ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des études histologiques antérieures ont montré que le follicle pileux est particulièrement susceptible de se calcifier, lorsque la peau de rats hypercalcémiques est lésée. Des analyses chimiques et par diffraction aux rayons X du follicule ont confirmé ce résultat. — En se basant sur l'augmentation du calcium et du phosphore, les calcifications débutent dans le tissue folliculaire 6–12 h après une blessure d'intensité moyenne de la peau de rats, ayant reçu du dihydrotachysterol (DHT), et 24–48 h après une blessure similaire chez des rats non injectés. Les diagrammes de diffraction aux rayons X sont diffus. Trois heures après la blessure, on note une augmentation du calcium du tissu folliculaire qui ne semble pas en rapport avec le DHT qui traduit probablement une liaison de calcium plutôt qu'un dépot minéral.
    Abstract: Zusammenfassung Frühere histologische Untersuchungen haben gezeigt, daß der Haarfollikel besonders anfällig für Verkalkungen ist, wenn die Haut von hypercalcämischen Ratten verletzt wird. Dieses Resultat wurde nun durch direkte chemische Bestimmungen und Röntgendiffraktions-analysen von Follikelgewebe bestätigt. Aufgrund der erhöhten Calcium- und Phosphatwerte kann gesagt werden, daß nach einer leichten Quetschung der Haut von Ratten, die mit Dihydrotachysterol (DHT) behandelt wurden, im Haarfollikelgewebe nach 6–12 Std Mineral-ablagerungen stattfanden, wogegen Kontrollratten mit der gleichen leichten Hautverletzung diese Ablagerungen erst nach 24–48 Std zeigten. Röntgendiffraktionsanalysen ergaben ein diffuses Apatit-Muster. Innerhalb 3 Std nach der Verletzung wurde ein Anstieg des Calcium-gehaltes im Follikelgewebe beobachtet, der nicht im Zusammenhang mit der DHT-Behandlung stand, also nicht eine Mineralablagerung, sondern eher eine Bindung von Calcium widerspiegelte.
    Notes: Abstract Previous histological investigations have shown that the hair follicle is particularly susceptible to mineralization when the skin of hypercalcaemic rats is injured. Direct chemical and X-ray diffraction analyses of follicle tissue have now confirmed this finding. As judged by increases in both calcium and phosphorus, mineral deposits began to form in hair follicle tissue 6–12 h after a mild crush injury to the skin of rats dosed with dihydrotachysterol (DHT), and 24–48 h after a similar injury to the skin of non-dosed rats. X-ray diffraction gave a diffuse apatite pattern. Within 3 h of injury there was a rise in the calcium content of follicle tissue which was not related to DHT-dosing and which was probably a reflection of calcium binding rather than mineral deposition.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 8 (1971), S. 304-319 
    ISSN: 1432-0827
    Keywords: Chemistry ; Calcium ; Phosphate ; Solubility ; Computer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un programme d'ordinateur a été mis au point pour calculer les activités ioniques du calcium et l'orthophosphate dans un grand nombre de solutions. Dans le cas de solutions synthétiques, les calculs sont vérifiés en comparant les valeurs de pH, obtenues par ordinateur, avec celles observées expérimentalement. Des essais de ce type, avec des solutions possèdant des concentrations de calcium et d'orthophosphate trouvées dans les liquides biologiques et à des valeurs de pH variant de 3.00 à 10.00, indiquent que le programme est adapté pour des applications biologiques. Le programme n'est pas effectif pour des solutions, dans les lesquelles l'ion bromure est la source principale de la force ionique, sans doute, par manque d'équation étendue de Debye-Hückel dans ces circonstances. Aucune formation de complexe de phosphate de sodium n'a été notée à des concentrations biologiques normales.
    Abstract: Zusammenfassung Es wurde ein Computer-Programm ausgearbeitet, um die Ionenaktivitäten von Calcium und Orthophosphat in einer breiten Varietät von Lösungen zu berechnen. Die Berechnungen wurden bei synthetischen Lösungen durch Vergleiche zwischen den auf diese Weise errechneten pH-Werten und den experimentell gefundenen kontrolliert. Diese Art Kontrollen mit Calcium-und Orthophosphatkonzentrationen, wie sie in biologischen Flüssigkeiten gefunden werden, und mit pH-Werten zwischen 3,0 und 10,0 wies darauf hin, daß das Programm für biologische Anwendungen geeignet war. Das Programm konnte nicht benützt werden für solche Lösungen, bei welchen hauptsächlich das Bromidion zur Einstellung der Ionenstärke verwendet wurde, vermutlich weil die erweiterte Debye-Hückel-Gleichung unter diesen Umständen nicht anwendbar ist. Die Bildung eines Natriumphosphat-Komplexes unter normalen biologischen Konzentrationen konnte nicht nachgewiesen werden.
    Notes: Abstract A computer program has been designed to calculate the ionic activities of calcium and orthophosphate in a wide variety of solutions. In the case of synthetic solutions the calculations were checked by comparing the computed pH values with those observed experimentally. Tests of this type with solutions having the concentrations of calcium and orthophosphate found in biological fluids and with pH values ranging from pH 3.0–10.0 indicated that the program was suitable for biological applications. The program was not effective for solutions in which the bromide ion was a principal source of ionic strength probably because of the failure of the extended Debye-Hückel equation under those circumstances. No evidence for the formation of any sodium phosphate complex at normal biological concentrations could be found.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 10 (1972), S. 171-197 
    ISSN: 1432-0827
    Keywords: Amorphous ; Crystalline ; Calcium phosphate ; Chemistry ; Composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des échantillons non lavés de phosphate de calcium amorphe (ACP) contiennent une fraction labile, non remplaçable, riche en phosphate acide avec un rapport Ca/P faible: cette fraction est perdue de façon irréversible au cours du lavage. De l'ACP frais, précipité entre pH 6.6–10.6, varie dans un rapport molaire Ca/P de 1.18 à 1.50 et dans un rapport HPO 4 2− /P total de 33.0% à 10.1%. A pH 7.40, de l'ACP frais a un rapport molaire Ca/P de 1.36±0.02 et contient 22.8 (±2.2)% HPO 4 2− . Les résultats obtenus avec du précipité non lavé ne peuvent s'expliquer par du Ca2+ emprisonné et de l'HPO 4 2− ou du Na+, Cl− et CO 3 2− exogènes. Les phosphates de calcium amorphes constituent une classe de sels ayant des caractères chimiques variables et des propriétés physiques identiques, comparables au verre. Le CaHPO4·xH2O non cristallin peut être un ACP, surtout au cours des phases précoces de formation. A des pH physiologiques, l'ACP se transforme en petits cristaux applatis contenant de fortes quantités de phosphate acide facilement remplaçable. Le fait de laver la couche de surface produit un changement chimique dans les nouveaux cristaux: des cristaux non lavés donnent des diagrammes de diffraction d'apatite peu cristallins, ainsi que des spectres infra-rouges peu nets, intermédiaires entre des apatites et du phosphate octocalcique. Des explications structurales sont proposées et les compositions minérales amorphe/cristalline de l'os et du cartilage sont recalculées.
    Abstract: Zusammenfassung Ungewaschene Proben von amorphem Calciumphosphat (ACP) enthalten eine unersetzliche labile Fraktion, welche reich an saurem Phosphat ist und ein niederes Ca/P-Verhältnis hat und welche während des Waschprozesses unwiderruflich verloren geht. Natives ACP, welches im pH-Bereich 6,6–10,6 ausgefällt wurde, variierte im molaren Ca/P-Verhältnis zwischen 1,18 und 1,50 und in HPO 4 2− /totales P zwischen 33,0 und 10,1%. Bei pH 7,40 hatte natives ACP ein molares Ca/P-Verhältnis von 1,36±0,02 und enthielt 22,8 (±2,2)% HPO 4 2− . Die Werte beim ungewaschenen Niederschlag rühren weder von aus dem Überstand aufgenommenem Ca2+ und HPO2−, noch von außen kommendem Na+, Cl− und CO 3 2− her. Die amorphen Calciumphosphate werden als eine Klasse von Salzen erkannt, welche veränderliche chemische, aber identische glasartige physicochemische Eigenschaften haben. Nicht kristallines CaHPO4·xH2O kann auch ein ACP sein, besonders in den frühen Bildungsstadien. Bei physiologischem pH verwandelt sich ACP in kleine plattenförmige Kristalle, welche große Mengen von leicht ersetzbarem saurem Phosphat enthalten. Das Waschen dieser Oberflächenschicht erzeugte chemische Veränderungen in den resultierenden Kristallen; ungewaschene Kristalle zeigten ein Diffraktionsmuster, das nur schwach demjenigen des kristallinen Aspatites glich, aber ein schlecht aufgelöstes Infrarotspektrum, welches zwischen Apatit und Octocalciumphosphat war. Es werden strukturelle Erklärungen für alle diese Phenomena diskutiert, und revidierte amorph/kristalline Mineralzusammensetzungen von Knochen und Knorpel wurden neu berechnet.
    Notes: Abstract Unwashed samples of amorphous calcium phosphate (ACP) contain an irreplaceable labile fraction, rich in acid phosphate and low in Ca/P ratio, which is irreversibly lost during the washing process. Native ACP precipitated in the pH range 6.6–10.6 varied in Ca/P molar ratio from 1.18 to 1.50 and in HPO 4 2− /total P from 33.0% to 10.1%. At pH 7.40, native ACP had a Ca/P molar ratio of 1.36±0.02 and contained 22.8 (±2.2)% HPO 4 2− . Unwashed precipitate data could not be attributed to either trapped supernatant Ca2+ and HPO 4 2− or extraneous Na+, Cl−, and CO 3 2− . The amorphous calcium phosphates are recognized as a class of salts having variable chemical but identical glass-like, physicochemical properties. Non-crystalline CaHPO4·xH2O may also be an ACP, especially during early formative stages. At physiological pH, ACP transforms to small platy crystals containing large amounts of readily-replaceable acid phosphate. Washing this surface layer produced chemical alterations in the resultant crystals; unwashed crystals had poorly-crystalline apatitic diffraction patterns but exhibited poorly-resolved infrared spectra intermediate between apatite and octacalcium phosphate. Structural explanations for all these phenomena are discussed, and revised bone and cartilage amorphous/crystalline mineral compositions have been re-calculated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 8 (1971), S. 197-210 
    ISSN: 1432-0827
    Keywords: Fluorescence ; Calcium ; Collagen ; Chemistry ; Bone ; Dentine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des composants fluorescents de l'os et la dentine sont séparés des hydrolysats alcalins de leur marice sur des colonnes Sephadex C25 CM d'échange cationique. Les concentrations en fluorescence et le spectre d'excitation (λ max 330 nm) et d'émission (λ max 395 nm) sont les mêmes que ceux observés au niveau des matrices intactes et gélatinisées. Les paramètres de fluorescence ne sont pas altérés par hydrolyse. La filtration sur gel à l'aide de colonnes Sephadex G 10 perment de différencier le matériel isolé en deux composants, ayant la même fluorescence et la même absorption UV. La fluorescence est indépendante de pH de 3.5–9.5. Des études de dialyse et de filtration sur gel de matrices gélatinisées indiquent une association étroite du matériel fluorescent avec les chaines polypeptidiques de collagène.
    Abstract: Zusammenfassung Fluorescierende Bestandteile aus Knochen und Dentin wurden in Sephadex C25 CM Kationen-Austauschersäulen von alkalischen Hydrolysaten ihrer Matrices getrennt. Die Fluorescenzintensitäten sowie die Erregungs- (λ max 330 nm) und Emissions- (λ max 395 nm) Spektren waren dieselben wie bei intakten und gelatinisierten Matrices. Die Fluorescenzparameter wurden durch die Hydrolyse nicht verändert. Eine Gelfiltration über Sephadex-G10-Säulen trennte das isolierte Material in 2 Komponenten auf, welche gleiche Fluorescenz- und UV-Absorptionseigenschaften zeigten. Im pH-Bereich zwischen 3,5 und 9,5 war die Fluorescenz unabhängig vom pH. Dialysierversuche sowie Gelfiltrationsexperimente mitden gelatinisierten Matrices zeigten eine starkgefügte Bindung des fluorescierenden Materials mit den Polypeptidketten des Kollagens.
    Notes: Abstract Fluorescent components in bone and dentine were separated from alkaline hydrolysates of their matrices on Sephadex C25 CM cationic exchange columns. The fluorescence levels, and the excitation (λ max 330 nm) and emission (λ max 395 nm) spectra, were the same as those observed in the intact and gelatinised matrices. The fluorescence parameters were unaltered by the hydrolysis procedure. Gel filtration on Sephadex G. 10 columns further resolved the isolated material into two components with the same fluorescence and UV absorption properties. The fluorescence was independent of pH over the range 3.5–9.5. Dialysis and gel filtration studies on the gelatinised matrices indicated a firmly-bonded association of the fluorescent material with the collagen polypeptide chains.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 8 (1971), S. 287-303 
    ISSN: 1432-0827
    Keywords: Calcification ; Bone ; Matrix ; Apatite ; Nucleation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Du collagène d'os compact de mouton est préparé par décalcification dans I'EDTA et à partir de tendons de queux de rats, par extraction dans l'acide acétique et reconstitution dans NaCl. Le dépôt d'apatite dans le collagène osseux de mouton dans une solution de calcification métastable est étudié chimiquement et par microscopie électronique. Le collagène osseux est un bon catalyseur de nucléation pour le dépôt minéral, alors que le collagène de tendons de rat ne l'est pas. Le dépôt minéral du collagène osseux se produit en deux phases cinétiques séparées, une phase rapide de nucléation et une croissance cristalline, donnant naissance à de petits ilots calcifiés et une seconde phase lente de croissance dans des régions ne comportant pas de zones catalytiques. La seconde phase de dépôt minéral paraît être le résultat d'une diffusion inhibée d'ions à travers les fibrilles collagènes alignées, laissant de larges régions de collagène sans minéral, bien que le tampon reste hautement sursaturé. La microscopie électronique permet de penser que les zones de catalyse pourraient avoir un rapport avec la périodicité de 640 Å de collagène, mais l'importance d'un matériel noncollagènique, lié au collagène, n'est pas à exclure. L'activité catalytique faible du collagène reconstitué n'est pas liée à la présence d'inhibiteurs faiblement liés, bien que des inhibiteurs puissent être intimement liés à ce type de collagène, qui pourrait être absent du collagène osseux. La différence d'activité catalytique pourrait intervenir dans la calcification physiologique. Une hypothèse plus générale pour la nucléation de la phase minérale dans les systémes biologiques est nécessaire.
    Abstract: Zusammenfassung Kollagen wurde aus kompaktem Schafsknochen mittels EDTA-Entkalkung und aus Rattenschwanzsehnen durch Essigsäureextraktion und Rekonstitution mit NaCl gewonnen. Die Apatitablagerung aus einer metastabilen Verkalkungslösung auf Schafsknochenkollagen wurde chemisch und im Elektronenmikroskop untersucht. Es zeigte sich, daß das Knochenkollagen ein guter Nukleationskatalysator für die Mineralablagerung ist, was beim Rattenschwanzkollagen nicht zutraf. Im Knochenkollagen erfolgte die Mineralablagerung in zwei getrennten kinetischen Phasen: einer raschen Phase der Nukleation und des Kristallwachstums, welche kleine verkalkte Inseln entstehen läßt, und einer zweiten langsamen Phase, welcher das Wachstum in Bezierken, die keine katalytischaktiven Stellen einschließen, zuzuschreiben ist. Diese zweite Phase der Mineralablagerung wird als Resultat einer verminderten Ionendiffusion durch die enganeinanderliegenden Kollagenfibrillen angesehen, wodurch weite Kollagenbereiche ohne Mineral bleiben, obwohl der Puffer stark übersättigt ist. Elektronenmikrographien ließen vermuten, daß die katalytischaktiven Stellen in einem gewissen Verhältnis zur 640 Å-Periodizität des Kollagens stehen; es konnte jedoch nicht ausgeschlossen werden, daß nicht-kollagenhaltiges Material, welches an Kollagen gebunden ist, ebenfalls eine Rolle spielt. Die schlechte katalytische Aktivität des rekonstituierten Kollagens konnte nicht auf die Anwesenheit von schwachgebundenen Hemmstoffen zurückgeführt werden, obwohl Inhibitoren stark an dieses Kollagen gebunden sein könnten, die jedoch im Knochenkollagen nicht vorhanden sind. Die Unterschiede in der katalytischen Aktivität können mit der physiologischen Verkalkung in Beziehung stehen. Eine allgemeinere Hypothese für die Nukleation einer Mineralphase in biologischen Systemen wäre erforderlich.
    Notes: Abstract Collagen was prepared from compact sheep bone by decalcification with EDTA and from rat tail tendons by acetic acid extraction and reconstitution with NaCl. The deposition of apatite in sheep bone collagen in a metastable calcification solution was studied chemically and by electron microscopy. The bone collagen was shown to be a good nucleation catalyst for mineral deposition, while rat tail collagen was a poor catalyst. Mineral deposition in bone collagen occured in two separate kinetic phases, a rapid phase of nucleation and crystal growth, giving rise to small calcified islands, and a second slow phase, ascribed to growth in regions not involving the catalytic sites. This second phase of mineral deposition is considered to be the result of impaired ion diffusion through the closely-aligned collagen fibrils, thus leaving large areas of the collagen free of mineral even though the buffer remains highly supersaturated. Electron micrographs suggested that the catalytic sites might be in some relationship to the 640 Å periodicity of collagen, but a role for non-collagenous material bound to the collagen has not been excluded. The poor catalytic activity of reconstituted collagen was not due to the presence of loosely-bound inhibitors, although inhibitors could be strongly bound to this type of collagen and be absent from bone collagen. The differences in catalytic activity may have a bearing on physiological calcification. A more general hypothesis for nucleation of a mineral phase in biological systems is required.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 12 (1973), S. 125-136 
    ISSN: 1432-0827
    Keywords: Mineralization ; Molt ; Isopod ; Chemistry ; Light microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Au cours de la phase inhabituelle de mue d'un isopode d'eau courante,Lirceuts brachyrus, la moitié postérieure de l'exosquelette est éliminée 24 heures avant la moitié antérieure. A ce stade, une reminéralisation se développe dans la partie postérieure alors que la partie antérieure est dans un stade de pré-mue. Le pourcentage de différence en calcium dans les deux moitiés à mi-mue et mue complète est respectivement de 22% (p〈0.01) et 33% (p〈0.01), indiquant une complexation du calcium pendant la mue. La rapidité de la reminéralisation est illustrée par le fait que le contenu minéral total double dans la partie postérieure entre la mi-mue et la mue totale et dans la partie antérieure entre la fin de la mue et un jour après. Le carbonate de calcium, sous forme de calcite, a pu être identifié par diffraction électronique de coupes fines des téguments.
    Abstract: Zusammenfassung Während der ungewöhnlichen Häutungssequenz des Frischwasser-IsopodenLirceus brachyurus (Harger) wird die hintere Hälfte des äußeren Skeletts 24 Std vor der vorderen Hälfte abgestoßen. In der halbgehäuteten Phase erfolgt Remineralisation im hinteren Teil, während der vordere Teil in einem Vorhäutungszustand ist. Der prozentuale Unterschied des Calciums in den zwei Hälften bei Halb- und Vollhäutungszustand ist 22% (p〈0,01) bzw. 33% (p〈0,01), was andeutet, daß Calcium während der Häutung abgesondert wird. Die Geschwindigkeit der Remineralisation erhellt aus der Tatsache, daß sich der Gesamtmineralgehalt im hinteren Teil zwischen Halt- und Vollhäutung, in der vorderen Hälfte jedoch zwischen Endhäutung und einem Tag nach der Häutung verdoppelt. Calciumcarbonat in kristalliner Calcitform wurde mittels Elektronendiffraktion von dünnen Hautschnitten nachgewiesen.
    Notes: Abstract During the unusual molt sequence of the fresh-water isopod,Lirceus brachyrus (Harger), the posterior half of the exoskeleton is shed 24 hours before the anterior half. At the half-molt stage, occurs in the posterior part while the anterior portion is in a pre-molt condition. The percentage difference in calcium in the two halves at half-molt and full-molt is22 (p〈0.01) and33 (p〈0.01) respectively, an indication that calcium is sequestered during The rapidity of remineralization is illustrated by the fact that the total mineral content doubles in the posterior part between half and full molt and in the anterior half between the end of molt and one day after ecdysis. Calcium carbonate in the calcite cystalline form was demonstrated by electron diffraction of thin sections of the integument.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 15 (1974), S. 213-220 
    ISSN: 1432-0827
    Keywords: Acid phosphatase ; Electron microscopy ; Shell Regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Acid phosphatase activity was mainly localized in the lysosomes in all the regions of the outer epithelium. The transitional portion of the outer epithelium showed more intense activity than the other regions. During shell regeneration the activity of this portion decreased to a minimum level at 12 hours and was restored to normal at 72 hours. The other regions showed no change of activity during shell regeneration. It is postulated that the acid phosphatase in the transitional protion is responsible for conferring calcifiability to the organic matrix of the shell.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 13 (1973), S. 259-270 
    ISSN: 1432-0827
    Keywords: Fluorapatite ; Exchange ; Chemistry ; Crystallography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un échantillon minéral provenant de Burgess, Canada s'est révélé être un speciment exceptionnellement pur de fluoroapatite après analyse chimique et cristallographique. La composition globale de cet échantillon est la suivante: $$(Ca^2 )9.98(Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )0.02(PO_4^{3 - } )5.98(HCO_3^ - ,CO_3^{2 - } )0.02(F^ - )2$$ . L'axe cristallographique C est de 6.865 A et l'axe a de 9.374 A. Des expériences d'échanges réalisés à l'aide de45Ca,32P et18F indiquent la présence de gros cristallites de surface spécifique de l'ordre de 1 m2/g. Il apparait que l'interprétation physique des processus d'échange ne nécessite pas l'existence de compartiments séparés, avec chacun son propre facteur cinétique, les échanges semblent être simplement liés à un changement exponentiel dans l'énergie libre de la réaction. Pour la réaction suivante: $$(Ca)_5 (PO_4 )_3 OH solide + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F solide + (OH^ - )$$ , la constante thermodynamique de 101.26 a été calculée, suggérant que le fluorapatite se forme toujours aux dépens de l'hydroxyapatite dans des conditions physiologiques. Cette transformation se continue en abaissant le pH.
    Abstract: Zusammenfassung Eine Mineralprobe aus Burgess, Kanada, erwies sich nach chemischer und kristallographischer Analyse als außergewöhnlich reines Fluorapatit. Die Gesamtzusammensetzung entspricht: $$(Ca^{2 + } )_{9,98} (Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )_{0,02} (PO_4^{3 - } )_{5,98} (HCO_3^ - ,CO_3^{2 - } )_{0,02} (F^ - )_2 $$ . Die kristallographische c-Achse wurde bestimmt und ergab 6,865 Å, und die a-Achse ergab 9,374 Å. Austauschwerte, welche durch Anwendung von45Ca,32P und18F erhalten wurden, deuteten auf große Kristalliten mit einer spezifischen Oberfläche von ca. 1 m2/g. Die Befunde deuten darauf hin, daß für die physikalische Erklärung des Austauschvorganges keine separaten Kompartimente mit eigenen kinetischen Faktoren nötig sind, sondern daß der Austausch mit dem exponentiellen Wechsel in der freien Energie der Reaktion in einfacher Beziehung steht. Für die Reaktion $$(Ca)_5 (PO_4 )_3 OH_{in fester Form} + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F_{in fester Form} + (OH^ - )$$ wurde als thermodynamische Konstante 101,26 errechnet, was darauf deutet, daß unter physiologischen Bedingungen immer Fluorapatit auf Kosten von Hydroxyapatit entsteht. Diese Umwandlung wird erhöht, wenn das pH erniedrigt wird.
    Notes: Abstract A mineral specimen from Burgess, Canada, proved upon chemical and crystallographic analyses to be an exceptionally pure sample of fluorapatite. The over-all composition corresponds to $$(Ca^{2 + } )_{9.98} (Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )_{0.02} (PO_4^{3 - } )_{5.98} (HCO_3^ - ,CO_3^{2 - } )_{0.02} (F^ - )_2 $$ . The crystallographic c-axis was determined to be 6.865 Å, and the a-axis 9.374 A. Exchange data obtained by employing45Ca,32P, and18F indicate the presence of large crystallites with a specific surface of the order of 1 m2/g. It is indicated that the physical interpretation of the exchange process does not require the existence of separate departments, each with its own kinetic factor, but that the exchange may be simply related to the exponential change in the free energy of the reaction. For the reaction $$(Ca)_5 (PO_4 )_3 OH_{solid} + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F_{solid} + (OH^ - )$$ the thermodynamic constant has been calculated to be 101.26, implying that fluorapatite always will form at the expense of hydroxyapatite under physiologic conditions. This transformation will be furthered by lowering the pH.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    ISSN: 1432-0827
    Keywords: Chondrocytes ; High-density suspension culture ; Electron microscopy ; Matrix vesicle ; Apatite formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Chondrocyte cultures grown in centrifuge tubes with intermittent centrifugation differentiate into hypertrophic chondrocytes and form calcification. We examined chondrocytes cultured in this system electron microscopically. Rat growth-plate chondrocytes were seeded in a plastic centrifuge tube and cultured in the presence of Eagle's minimum essential medium supplemented with 10% fetal bovine serum and 50 μg of ascorbic acid per ml. Specimens were examined by using electron microscopy and selected-area electron-diffraction techniques. In the early stage of culture, a few chondrocytes were scattered and extracellular matrices were not observed. In the middle stage of the cultures, the chondrocytes resembled proliferative cells. Matrix vesicles appeared to be budding from the cell surfaces of chondrocytes and were observed sparsely in the extracellular matrices, which were well formed around the chondrocytes. Matrix vesicles increased substantially during the following cultures. In the mature stage of the cultures, crystal formation related to matrix vesicles was observed. In the 33-day cultures, several masses of calcified matrix were formed and it was confirmed to be apatite by selected-area electron diffraction analysis. The chondrocytes appeared hypertrophic during this same stage. The 56-day culture was similar to the 33-day culture. It was concluded that this culture system provides an extracellular-matrix mineralization which is produced by chondrocytes per se.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    ISSN: 1432-2048
    Keywords: Bradyrhizobium ; Electron microscopy ; Glycine (root nodules) ; High-pressure freezing ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract High-pressure freezing of chemically untreated nodules of soybean (Glycine max (L.) Merr.), in sharp contrast to chemical fixation and prefixation, appears to preserve the ultrastructure close to the native state. This is supported by the observation that the peribacteroid membrane of high-pressure-frozen samples is tightly wrapped around the bacteroids, a finding that is fully consistent with the current views on the physiology of oxygen and metabolite transport between plant cytosol and bacteroids. In soybean root nodules, the plant tissue and the enclosed bacteria are so dissimilar that conventional aldehyde-fixation procedures are unable to preserve the overall native ultrastructure. This was demonstrated by high-pressure freezing of nodules that had been pre-fixed in glutaraldehyde at various buffer molalities: no buffer strength tested preserved all ultrastructural aspects that could be seen after high-pressure freezing of chemically untreated nodules.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 17 (1994), S. 1-8 
    ISSN: 1432-0789
    Keywords: Ammonium excretion ; Azospirillum brasilense ; Auxine ; 2,4-Dichlor-phenoxy-acetic acid ; Nitrogen fixation ; Paranodulation ; Maize ; Zea mays ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize seedlings develop nodule-like tumour knots (para-nodules) along primary roots when treated with the auxin 2,4-dichlor-phenoxy-acetic acid (2,4-D). Inoculated NH 4 + -excreting Azospirillum brasilense cells were shown to colonize these tumours, mostly intracellularly, promoting a high level of N2 fixation when microaerophilic conditions were imposed. The nitrogenase activity inside the para-nodules was less sensitive to free O2 than in non-para-nodulating roots. Both light and electron microscopy showed a dense bacterial population inside intact tumour cells, with the major part of the cell infection along a central tumour tissue. The bacteria colonized the cytoplasm with a close attachment to inner cell membranes. In an auxin-free growth medium, young 2,4-D-induced para-nodules grew further to become mature differentiated root organs in which introduced bacteria survived with a stable population. These results provide evidence that gramineous plants are potentially able to create a symbiosis with diazotrophic bacteria in which the NH 4 + -excreting symbiont will colonize para-nodule tissue intracellularly, thus becoming well protected.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Springer
    Machine vision and applications 4 (1991), S. 271-285 
    ISSN: 1432-1769
    Keywords: Electron microscopy ; three-dimensional vision ; surface reconstruction ; stereo ; shape from shading ; dynamic programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The computational reconstruction of surface topographies from scanning electron microscope (SEM) images has been extensively investigated in the past, but fundamental image processing problems still exist. Since conventional approaches adapted from general-purpose image processing have not sufficiently met the requirements in terms of resolution and reliability, we have explored combining different methods to obtain better results. This paper presents a least-squares combination of conventional stereoscopy with “shape from shading” and a way of obtaining self-consistent surface profiles from stereoscopy and “stereo-intrinsic shape from shading” using dynamic programming techniques. Results are presented showing how this combined analysis of multi-sensorial data yields improvements of the reconstructed surface topography that cannot be obtained from individual sensor signals alone.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 160 (1993), S. 284-287 
    ISSN: 1432-072X
    Keywords: Bacterial glucoamylase ; Clostridium thermosacharolyticum ; Cellular location ; Activity states ; Macromolecular organization ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By application of immunocytochemical techniques at the electron microscope level, glucoamylase was localized to the cell periphery in Clostridium thermosaccharolyticum during and following growth on starch, sucrose or glucose. Levels of immunolabelling were found to be relatively independent of growth substrate and of phase of growth, whereas previous studies had demonstrated strong dependence of glucoamylase activity on growth conditions; previously high levels of glucoamylase activity had been detected after growth on starch (i.e. during the stationary phase after growth) and only very low activities detected during exponential growth and following growth on glucose. The results presented demonstrate that levels of the glucoamylase protein are independent of measurable enzyme activity, and imply that the protein is constitutive. This indicates that the protein can exist in active and inactive states in the cell. By analogy with similar systems, we consider it likely that “maturation” or “activation” of newly synthesized glucoamylase occurs during (or following) transport through the cytoplasmic membrane. Electron microscopy of individual protein molecules which had been subjected to negative staining revealed that the enzyme consists of two domains of approximately equal size which are linked by a “hinge” region.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    ISSN: 1432-072X
    Keywords: Soluble NAD-dependent hydrogenase ; Alcaligenes eutrophus ; Nocardia opaca ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The soluble NAD-dependent hydrogenase (hydrogen-NAD oxidoreductase, EC 1.12.1.2), consisting of four non-identical subunits, was isolated from Alcaligenes eutrophus H16 and from Nocardia opaca 1b and analyzed by a HPLC gel permeation technique and electron microscopy. The tetrameric enzyme particles from both origins, as determined from negatively stained electron microscopic samples, were found to be elongated and very similar in shape and size. The A. eutrophus enzyme was measured in more detail. It exhibited dimensions of 12.7 nm by 5.5 nm (axial ratio 2.3:1). Dissociation into smaller particles and unspecific aggregation combined with partial inactivation were observed in the presence of the inhibitor NADH. Kept in buffer without added nickel, the enzyme was partially dissociated. Reassociation of tetramers without restored enzyme activity was achieved by addition of 0.5 mM NiCl2. A working model for the structural organization of the tetrameric enzyme particle is presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    ISSN: 1432-072X
    Keywords: Trichoderma reesei ; Xylanase ; Ultrastructural localization ; Immunogold labelling ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The intracellular location of the “low-molecular weight, alkaline” xylanase (XYN II) of Trichoderma reesei RUT C-30 was investigated during growth on xylan, using immunoelectron microscopy. A monoclonal antibody, produced against XYN II, was used for this purpose. The enzyme was found at the endoplasmic reticulum and in electron dense 0.2 to 0.8 μm vesicles, as well as in the vacuole, at the plasma membrane and in the fungal cell-wall. No staining occured in the cytoplasm, the mitochondria and the nucleus. No Golgi-like structures could be seen. Addition of the carboxylic ionophore monensin blocked xylanase as well as total protein secretion. The results are discussed with respect to XYN II being secreted by T. reesei via a pathway involving the endoplasmic reticulum and secretory vesicles and/or the vacuole.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    ISSN: 1432-072X
    Keywords: Malonomonas rubra ; Propionigenium modestum ; Malonate decarboxylase ; Methylmalonyl-CoA decarboxylase ; Biotin ; Avidin ; Electron microscopy ; High pressure freezing ; Immunolabeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Malonate decarboxylase of Malonomonas rubra is a complex enzyme system involving cytoplasmic and membrane-bound components. One of these is a biotin-containing protein of Mr 120'000, the location of which in the cytoplasm was deduced from the following criteria: (i) If the cytoplasm was incubated with avidin and the malonate decarboxylase subsequently completed with the membrane fraction the decarboxylase activity was abolished. The corresponding incubation of the membrane with avidin, however, was without effect. (ii) Western blot analysis identified the single biotin-containing polypeptide of Mr 120'000 within the cytoplasm. (iii) Transmission electron micrographs of immuno-gold labeled M. rubra cells clearly showed the location of the biotinyl protein within the cytoplasm, whereas the same procedure with Propionigenium modestum cells indicated the location of the biotin enzyme methylmalonyl-CoA decarboxylase in the cell membrane. The biotin-containing protein of the M. rubra malonate decarboxylase enzyme system was not retained by monomeric avidin-Sepharose columns but could be isolated with this column in a catalytically inactive form in the presence of detergents. If the high binding affinity of tetrameric avidin towards biotin was reduced by destructing part of the tryptophan residues by irradiation or oxidation with periodate, the inhibition of malonate decarboxylase by the modified avidin was partially reversed with an excess of biotin. Attempts to purify the biotin protein in its catalytically active state using modified avidin columns were without success.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 159 (1993), S. 114-118 
    ISSN: 1432-072X
    Keywords: Bacillus pulvifaciens ; Vegetative cells ; Spotes ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructure of vegetative cells and spores of Bacillus pulvifaciens was studied by CTEM and SEM methods. The vegetative cells are rods, 1.6–4.5 μm long and 0.4–0.6 μm wide, exhibiting typical ultrastructural features of Gram-positive bacteria. The spores are of ellipsoidal shape, 0.6×1.2 μm in size, with six longitudinal ribs reaching up to 130 nm in height. There are satelite ribs on both sides of the longitudinal ribs, reaching up to 20 nm in height. Between the longitudinal ribs, additional transversal ribs were observed in SEM. A special tubular layer, separating the outer and inner coat of the spores, was revealed in ultrathin sections. This layer seems to be a typical ultrastructural feature of Bacillus pulvifaciens spores.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 157 (1992), S. 381-388 
    ISSN: 1432-072X
    Keywords: PhiX174 ; Bacterial lysis ; Escherichia coli ; Electron microscopy ; Membranes ; Cell envelope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of cloned gene E of bacteriophage PhiX174 induces lysis by formation of a transmembrane tunnel structure in the cell envelope of Escherichia coli. Ultrastructural studies of the location of the lysis tunnel indicate that it is preferentially located at the septum or at polar regions of the cell. Furthermore, the diameter and shape of individual tunnel structures vary greatly indicating that its structure is not rigid. Apparently, the contours of individual lysis tunnels are determined by enlarged meshes in the peptidoglycan net and the force produced at its orifice, by the outflow of cytoplasmic content. Once the tunnel is formed the driving force for the lysis process is the osmotic pressure difference between cytoplasm and medium. During the lysis process areas of the cytoplasmic membrane which are not tightly attached to the envelope are extended inward by the negative pressure produced during lysis. After cell lysis external medium can diffuse through the lysis tunnel filling the inner cell space of the still rigid bacterial ghosts.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    ISSN: 1432-072X
    Keywords: Lactobacillus ; Medium composition ; Metal cations ; Electron microscopy ; Protoplast-like forms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of some locally isolated Lactobacillus strains forming D(-) or L(+) lactic acid, Lactobacillus helveticus ATCC 15009 and Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842 was examined in different media. L. helveticus and Lactobacillus LBL strains formed atypical protoplast-like cells in LAPT medium, sensitive to SDS and proteinase. Specific morphological changes in the cell wall structure of these variants were revealed by transmission and scanning electron microscopy. The effect of glucose and various salts on their appearance was investigated. The prevalent role of metal cations, especially of Mg2+, was established.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 160 (1993), S. 206-213 
    ISSN: 1432-072X
    Keywords: Treponema denticola ; Spirochetes ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The formation of quasi-multicellular bodies of Treponema denticola was analysed using different electron microscopical methods. These bacteria could develop four different conformations: (i) normal helical forms; (ii) twisted spirochetes, forming plaits; (iii) twisted spirochetes, forming club-like structures; (iv) spherical bodies in different size. Treponemes within spherical bodies, plaits, and clubs proved to be enclosed in a common outer sheath in which the normal arrangement of their axial flagella was lost. The development of the quasi-multicellular bodies starting from the monoforme spirochetes was elucidated and this morphogenetic process is illustrated by a schematic drawing. Factors which might be involved in the induction of the structures are discussed and their possible pathogenetic importance is considered.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 162 (1994), S. 267-271 
    ISSN: 1432-072X
    Keywords: Key words     Extremely thermophilic eubacterium ; Calderobacterium hydrogenophilium ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract       Calderobacterium hydrogenophilum is an extreme thermophilic, obligately chemoautotrophic, hydrogen-oxidizing bacterium. The cells were shown to be non-motile straight rods of average size 0.4 × 2.5 μm. After negative-staining of the whole cells, no flagella were observed. The multilayered cell wall was of type 1 and possessed a crystalline proteinaceous surface layer exhibiting p4 symmetry. The square unit cells had a lattice constant of approximately 11 nm. Cell division occurred by a constriction mechanism. C. hydrogenophilum differred from a similar hydrogen-oxidizing eubacterium, Hydrogenobacter thermophilus, by the absence of intracytoplasmic membrane structures in chemically fixed cells. However, an electron-dense intracytoplasmic hemispherical structure adhering to the inner membrane was frequently observed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 162 (1994), S. 267-271 
    ISSN: 1432-072X
    Keywords: Extremely thermophilic eubacterium ; Calderobacterium hydrogenophilium ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Calderobacterium hydrogenophilum is an extreme thermophilic, obligately chemoautotrophic, hydrogen-oxidizing bacterium. The cells were shown to be nonmotile straight rods of average size 0.4x2.5 μm. After negative-staining of the whole cells, no flagella were observed. The multilayered cell wall was of type 1 and possessed a crystalline proteinaceous surface layer exhibiting p4 symmetry. The square unit cells had a lattice constant of approximately 11 nm. Cell division occurred by a constriction mechanism. C. hydrogenophilum differred from a similar hydrogen-oxidizing eubacterium, Hydrogenobacter thermophilus, by the absence of intracytoplasmic membrane structures in chemically fixed cells. However, an electron-dense intracytoplasmic hemispherical structure adhering to the inner membrane was frequently observed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 216 (1994), S. 153-154 
    ISSN: 1572-946X
    Keywords: Chemistry ; Molecular Hydrogen ; Cloud Models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations of the CO J=1-0 line are commonly used as a tracer for molecular material in clouds. The ratio of the H2 column density to the integrated intensity of this line,X, is often taken to be constant, despite theoretical and observational uncertainty. We have tried to identify how this ratio depends on cloud parameters, testing a simple theoretical argument suggesting its invariance with respect to density. The apparent constancy can be understood if clouds are clumpy on scales of Av ≈ 1-2 mag.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    ISSN: 1573-4935
    Keywords: Transferrin ; Receptor ; Isolation ; Reconstitution ; Liposomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Human transferrin receptor was isolated from Triton X-100 solubilized placental plasma membranes by a rapid one-step chromatographic procedure based on immunoadsorption of the receptortransferrin complex on anti-transferrin Sepharose and lectin-affinity on wheat germ agglutinin. Following exchange of Triton X-100 with CHAPS or n-octylglucoside, the purified receptor was incorporated into egg phosphatidylcholine liposomes upon, detergent removal by dialysis (lipid/protein ratio 15:1 to 45:1 (w/w) Reconstitution of the receptor was confirmed by trypsin cleavage to dissociate the large extracellular receptor domain from the liposomal membranes. Electron micrographs of the receptor-lipid recombinants negatively stained with sodium sillicotungstate, showed ographs of the receptor-lipid recombinants negatively stained with sodium sillicotungstate, showed that the receptor molecules distributed very inhomogeneously on the liposomes, most receptors being clustered. Single copies of the receptor were seen as elongate structures (5×10 nm) oriented with their long axis parallel to the liposome surface and separated from this by a 2–3 nm gap. This result provides evidence for a narrow connecting link between the globular extracellular receptor domain and the membrane spanning segment.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Springer
    Bioscience reports 12 (1992), S. 495-501 
    ISSN: 1573-4935
    Keywords: Electron microscopy ; secretion ; neuropeptides ; exocytosis ; endocytosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Exo- and endocytotic processes induced by depolarization of isolated neurosecretory nerve terminals show a close temporal correlation, which suggests a short time of integration of the neurosecretory granule membrane with the plasma membrane. In order to determine minimal time requirements for exocytosis-coupled endocytosis to occur, we have analyzed by electron microscopy uptake of horserdish peroxidase (HRP) as a fluid phase marker at the onset of depolarization. We have applied rapid mixing and sampling (quenched flow) to assess events in subsecond time peroids after stimulation. A significant number of labelled endocytotic vacuoles was observed during the first second of depolarization. This number then further increased by a factor of about 2 (within 5 s) and 4 (within 50s). Thus, as for exocytosis, the rate of endocytosis decreased considerably during prolonged stimulation. These data indicate i) that a substantial proportion of secretory granules undergoes exocytosis very shortly after stimulation, and ii) that, following exocytosis, the minimal time required for consecutive membrane retrieval is in the sub-second range.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 140 (1994), S. 215-223 
    ISSN: 1432-1424
    Keywords: Insulin receptor ; Membrane reconstitution ; Electron microscopy ; Quaternary structure ; Immunogold labeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Insulin receptors were incorporated into liposomes by two different procedures, one using dialysis and one using detergent removal by Bio-Beads. Receptor incorporation was analyzed by gradient centrifugation and electron microscopy. Reconstituted receptors projected up to 12 nm above the membrane and exhibited a T-shaped structure compatible with that previously described for the solubilized receptor. Insulin binding and autophosphorylation experiments indicated that approx. 50% of the receptors were incorporated right-side out. Such random orientation was confirmed by immunogold labeling of the α- and the β-subunit of the receptor. Immunogold labeling of the C-terminus of the β-subunit indicates that it resides about 6 nm off the membrane, while two α-subunit epitopes were labeled at about twice this distance, confirming that the α-subunit is harbored in the cross-bar of the T-structure.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 111 (1970), S. 316-345 
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Histophysiology of median eminence ; Avian neurohypophysis ; Neurosecretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les effets de l'adénohypophysectomie et de diverses sollicitations de l'axe hypothalamo-hypophysio-corticosurrénalien sur l'ultrastructure de l'Eminence Médiane (E.M.) ont été étudiés chez le Pigeon. 1. Chez le Pigeon entier, l'Eminence Médiane Caudale (E.M.C.) se distingue de l'Eminence Médiane Rostrale (E.M.R.) essentiellement par l'absence dans les deux couches les plus externes (couches palissadique et superficielle) de l'E.M.C. de granules de gros calibres (1600 à 1900 Å), la rareté de granules de diamètre moyen (1200–1400 Å) et la prédominance de petites vésicules à cœur dense de 600–800 Å. 2. La préhypophysectomie entraine: a) dans l'E.M.R. la quasi disparition de granulations dans les deux couches externes; b) dans l'E.M.C. la ≪vidange≫ de nombreux axones, mais un enrichissement relatif, parmi les granulations restantes, des granulations de gros calibre (1600–1900 Å) aux dépens des granules de plus petit calibre. 3. Un shock insulinique entraine des modifications du même ordre: a) déplétion des granules denses, limitée dans ce cas à la portion la plus antérieure des deux couches externes de l'E.M.R.; b) enrichissement relatif des granulations de moyen (1200–1400 Å) et de gros (1600–1900 Å) calibre dans l'E.M.C. avec, en plus dans l'E.M.C., un enrichissement en vésicules de type synaptique. 4. Un traitement à la métopirone produit un accroissement du nombre des granulations de moyen (1200–1400 Å) calibre dans les couches externes de l'E.M.R. et de l'E.M.C., et un enrichissement important de l'E.M.C. en vésicules de type synaptique. 5. Le traitement à la prednisolone conduit à un enrichissement très marqué des couches externes de l'E.M.R. en grains de 1200–1400 Å, et à un enrichissement des couches externes de l'E.M.C. en granulations de 1000 Å. Ces résultats sont discutés dans la perspective des régulations hypothalamo-corticotropes, particulièrement en ce qui concerne les granules de 1200–1400 Å.
    Notes: Summary The effects of adenohypophysectomy, and of several experimental interventions on the hypothalamo-pituitary-adrenal cortical axis have been studied in relation to the fine structure of the median eminence in the pigeon. 1. In control animals, the following morphological features of the caudal median eminence (C.M.E.) distinguish it from the rostral median eminence (R.M.E.): a) the absence in both external layers of the C.M.E. of large (1,600–1,900 Å) electron-dense granules, b) the presence in the C.M.E. of a small number of medium-size (1,200–1,400 Å) granules, and c) the predominance in the C.M.E. of small (600–800 Å) dense-core vesicles. 2. Adenohypophysectomy leads to: a) almost complete disappearance of electron-dense granules in both external layers of the R.M.E., and b) “emptying” of numerous axons and a relative increase in the number of large (1,600–1,900 Å) granules in the C.M.E. 3. Insulin shock produces modifications similar to those of adenohypophysectomy. The depletion of electron-dense granules from the axons is, however, restricted to the most anterior part of the R.M.E., and, in the C.M.E., the relative increase in the number of larger granules affects the 1,200–1,400 Å and the 1,600–1,900 Å size granules. 4. Metopirone enhances the number of medium-size (1,200–1,400 Å) granules in the external layers of both the R.M.E. and the C.M.E. and causes a significant increase in the number of synaptic-like vesicles in the C.M.E. 5. Prednisolone treatment leads to a marked enrichment of the external layers of the R.M.E. with 1,200–1,400 Å granules, and of the external layers of the C.M.E. with 1,000 Å granules. These results have been discussed with special reference to the hypothalamic control of the adrenocorticotropic function, especially reviewing the role of the 1,200–1,400 Å granules.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 114 (1971), S. 61-72 
    ISSN: 1432-0878
    Keywords: Corpora cardiaca ; Neurosecretion ; Insects ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les corpora cardiaca de l'adulte de Locusta migratoria sont formés de deux régions bien individualisées ce qui nous a permis de reconnaître la sécrétion propre des différents types de neurosécrétion. Dans la région nerveuse, nous distinguons par la taille des grains trois types de neurosécrétion dense classique et un quatrième type d'aspect clair. Dans la région »propre« non nerveuse, les cellules ont des caractères nettement endocriniens et sont mélangées à un seul type d'axones neurosécréteurs.
    Notes: Summary The corpora cardiaca of adult Locusta migratoria consist of two well separated areas, a fact which permits the differentiation between intrinsic and extrinsic neurosecretory material. In the neural area three types of electron dense “classical” neurosecretory granules, and a fourth more lucent type can be distinguished according to size. In the non-neural “glandular” area typical endocrine cells mingle with only one type of neurosecretory axons.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 115 (1971), S. 565-578 
    ISSN: 1432-0878
    Keywords: Testis ; Reptiles ; Sertoli cells ; Glycogen ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les cellules de Sertoli du testicule de Lacerta vivipara ont été étudiées en microscopie électronique chez des animaux récoltés entre le printemps et l'automne pendant deux années et chez des animaux hypophysectomisés en automne. Ces cellules contiennent de nombreuses mitochondries de petite taille à crêtes lamellaires, des ribosomes libres, un reticulum endoplasmique lisse moyennement développé, plusieurs petits dictyosomes formant l'appareil de Golgi, des liposomes et des microtubules. Elles renferment aussi de nombreux corps denses de grande taille qui paraissent être de nature lysosomiale. Le glycogène a été particulièrement étudié. Il est formé de particules β dispersées au hasard dans le hyaloplasme. Des variations saisonnières dans la teneur en glycogène ont été notées. Chez les hypophysectomisés, les cellules de Sertoli contiennent de grandes quantités de ce métabolite dont les particules sont concentrées dans des petites plages, souvent autour des liposomes. Les rôles possibles des cellules de Sertoli sont discutés: soutien et apport de nourriture aux cellules germinales, production d'hormones et phagocytose des corps résiduels. Les variations de la teneur en glycogène sont également discutées.
    Notes: Summary Sertoli cells of the testis of Lacerta vivipara have been studied electron microscopically in animals obtained between spring and autumn during two years and in animals hypophysectomized in autumn. These cells contain numerous small mitochondria with lamellar cristae, free ribosomes, smooth endoplasmic reticulum moderately developed, several small dictyosomes forming the Golgi complex, lipid droplets and microtubules. There are numerous dense bodies of large size with an heterogeneous content which seem to be of lysosomial nature. Glycogen consists of β particles dispersed at random in the hyaloplasm. Seasonal variations in the content of glycogen are noted. In hypophysectomized animals Sertoli cells contain large amounts of that metabolite whose particles are concentrated in small areas often around the lipid droplets. Possible role of the Sertoli cells concerning mechanical support and nutrition of the germinal cells, production of hormones and phagocytosis of residual bodies are discussed. The variations in the glycogen content are also discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 118 (1971), S. 97-112 
    ISSN: 1432-0878
    Keywords: Stratum corneum ; Man ; Non-fixed ; Non-dehydrated ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This is an electron microscopic study of non-fixed and non-dehydrated normal human stratum corneum from the lumbar region. Non-stained sections have a low contrast. In sections examined 3 days after skin biopsy the cytoplasm of the cells shows a uniform contrast or exhibits dark and light areas. A single layer delimits the cytoplasm from the intercellular space. The latter is partly filled out with substance. In sections stained 2 to 4 days after skin biopsy the fibrils are distinct. On the basis of the variations in their opacity and ultrastructure three types of horny cells are clearly distinguishable. In cells of type 1 intensely stained keratohyalin and less opaque fibrillar substance occur. A distinct keratin pattern is not found. In cells of type 2 the fibrils show areas with distinct kerytohyalin and keratin pattern and transitional phases between these two stages of fibrillar differentiation. The keratin pattern representing the final stage of the fibrillar differentiation process is visualized through a successive “discoloration” of the filaments, whereas the interfilamentous substance retains the opacity of the keratohyalin. In cells of type 3 the entire fibrillar substance exhibits a keratin pattern. This consists of less opaque filaments with a diameter of 74 Å. The septa representing the interfilamentous substance are estimated as 30 Å at their thinnest points. These observations of the fibrils are completely comparable to the findings in fixed and dehydrated normal human stratum corneum. In sections stained particularly more than 18 days after skin biopsy the fibrils exhibit pronounced changes in their staining properties with concomitant decrease in distinctness or a complete extinction of the keratin pattern. The observations of the modified plasma membrane and the intercellular space in stained sections correspond to the findings in fixed and dehydrated normal human stratum corneum. The modified plasma membrane and the structures in the intercellular space appear with equal distinctness, whether the sections are stained 2 to 4, 6 to 12 or 14 to 21 days after skin biopsy.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 118 (1971), S. 467-481 
    ISSN: 1432-0878
    Keywords: Neutrophilic promyelocyte ; Human bone marrow ; Primary granulogenesis ; Phase contrast microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The developmental changes in the neutrophilic promyelocytes from normal human bone marrow have been analyzed by means of phase contrast and electron microscopy. This developmental phase is characterized by the elaboration of primary (azurophillysosomal) granules and the entire intracellular machinery is directed principally toward this goal. The promyelocyte stage has been subdivided into three arbitrary stages based upon morphological, histochemical and functional characteristics which relate to the onset, active production and cessation of primary granulogenesis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 119 (1971), S. 120-146 
    ISSN: 1432-0878
    Keywords: Red muscle ; Fibre types ; Small mammals ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Fasern des roten und langsamen M. soleus von Ratte, Kaninchen und Katze und des roten, jedoch schnellen, M. vocalis des Kaninchens wurden licht- und elektronenmikroskopisch untersucht und mit den verschiedenen Fasertypen aus dem M. tibialis anterior der Ratte und dem M. gastrocnemius des Kaninchens und der Katze verglichen. M. soleus und M. vocalis (einschließlich M. thyreoarytenoideus) enthalten nur einen mitochondrienreichen Fasertyp. Im schnellen M. vocalis ist der Z-Streifen schmal (50–60 nm), das sarcoplasmatische Reticulum ist gut entwickelt. Die Anordnung von Reticulum und Mitochondrion ist ähnlich wie in Herzmuskelzellen. Wie auch in anderen langsamen Muskeln verschiedener Tiere ist im M. soleus der Z-Streifen breit (100–120 nm), Triaden und Reticulum sind selten, und die Filamente bilden unregelmäßige Areale anstelle von Fibrillen. Hierin gleichen die Fasern des M. soleus den (mitochondrienreichen) C-Fasern eines entsprechenden gemischten Muskels; dagegen zeigen die Zwischentyp-(B-)Fasern schmale Z-Linien (50–70 nm), isodiametrische Fibrillen und mehr Triaden als die C-Fasern. Entgegen der bisherigen Vermutung, die auf der histochemischen Zuordnung der SoleusFasern zum Typ B und der Vocalis-Fasern zum Typ C beruht, ist daher anzunehmen, daß die langsamen motorischen Einheiten eines gemischten Muskels aus C- und nicht aus B-Fasern bestehen. In einigen Muskeln sind die Sarcomere der C-Fasern länger als die der B-(und A-) Fasern. Im M. tibialis anterior der Ratte verschwindet der Unterschied von 8,5% bei 2,6 μm Sarcomerlänge bei der Dehnung auf 2,8 μm mittlere Sarcomerlänge; vermutlich weil die Ruhedehnungskurve zunehmend steiler wird. Die isometrische Extraspannung im Tetanus ist bei 120% der Ruhelänge, d.h. bei 2,7 μm Sarcomerlänge. am größten. Daher muß bei 2,6 μm mittlerer Sarcomerlänge die Kraft der C-Fasern die der B-Fasern übertreffen. Rote Muskeln sind besser vaskularisiert als weiße Muskeln. Für die Mm. soleus und gastrocnemius der Katze verhalten sich die Kapillardichten (Kapillaren/mm2 Muskelfaserquerschnitt) wie 2,7∶:1. Dieser Wert entspricht dem Verhältnis zwischen den Größen für die Durchblutung (ml/min × 100 g) in Ruhe und bei maximaler Gefäßerweiterung.
    Notes: Summary Muscle fibres of the red and slow contracting soleus of rat, rabbit and cat and of the red however fast contracting thyreoarytenoid of rabbit are compared with different fibre types in the anterior tibial muscle of rat and in the gastrocnemius of rabbit and cat. With respect to fibre types soleus and thyreoarytenoid (including m. vocalis) are homogeneous and both being rich in mitochondria. The fast thyreoarytenoid shows a narrow Z-line (50–60 nm) and a well developed sarcoplasmic reticulum. The pattern of reticulum and mitochondria resembles more that of heart muscle cells than of skeletal muscle fibres. Like many slow contracting muscles of different animals the soleus fibres display a wide Z-line (100–120 nm), few triads, little reticulum and irregularly shaped areas of myofilaments instead of fibrils. In that soleus fibres equal fibres of type C (rich in mitochondria) in a corresponding heterogeneous muscle, whereas intermediate (type B) fibres reveal narrow Z-lines (50–70 nm), isodiametrically shaped myofibrils and more triads than C-fibres. Therefore it is far more likely that the slow motor units of a mixed muscle consist of C-fibres than of B-fibres. This is at variance with the histochemical designation of soleus fibres as type B and thyreoarytenoid fibres as type C. In some muscles in C-fibres the sarcomeres are longer than in B-(and A-)fibres. In the anterior tibial muscle of rat this difference is 8.5% at a mean sarcomere length of 2.6 μm, and disappears at a mean length of 2.8 μm, probably due to the steeper slope of the length tension diagram at rest. Since the isometric extratension in a tetanus is highest at 120% resting length (corresponding to about 2.7 μm sarcomere length), the force of C-fibres exceeds that of B-fibres at 2.6 μm but not at 2.8 μm sarcomere length. Red and white muscle differ with respect to vascularisation. The relation between the densities of capillaries in soleus and gastrocnemius of cat is 2.7∶:1 and equals the relation between the blood flows through these muscles during rest and maximum vasodilatation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 123 (1972), S. 47-54 
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Neurohypophysis ; Exocytosis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Elektronenmikroskopische Untersuchungen an der Neurohypophyse von Ratte und Forelle ergeben, daß sich eine Exocytose von Elementargranula an den Endigungen der neurosekretorischen Fasern nur selten abspielt. Es wird daher angenommen, daß die Abgabe von Hormonen in der Neurohypophyse in der Regel nach dem Muster des „membrane-release“ abläuft. 2. Die Exocytose wird nicht durch eine unmittelbare tangentiale Fusion der Membran des Elementargranulums mit dem Plasmalemm der Nervenendigung (Axolemm) eingeleitet. Vor allem bei Anwendung eines Goniometertisches wird erkennbar, daß vor der Exocytose zwischen Axolemm und Membran des Granulums eine Verbindung in Gestalt eines Stieles entsteht. Die Länge dieses Verbindungsstückes entspricht etwa 2 Axolemmdicken. An der Basis des Stiels im Axolemm tritt das Stoma auf, durch das der Inhalt des Granulums bzw. dieses selbst das Axonende verläßt. 3. Die Herkunft kleiner membrannaher Vesikel (Durchmesser 500 Å) in den Endigungen neurosekretorischer Nervenfasern in der Neurohypophyse konnte nicht geklärt werden. Anzeichen einer kompensatorischen Endocytose im Sinne von Nagasawa, Douglas und Schulz (1970) wurden nicht beobachtet.
    Notes: Summary 1. Electron microscopical investigations of the neurohypophysis in rat and trout reveal that exocytosis of neurosecretory elementary granules from the nerve endings occurs only rarely. The authors are of the opinion that hormone release in the neural lobe follows mainly the “membrane-release” pattern. 2. Exocytosis is not performed by tangential fusion of the elementary granule membrane and the plasmalemma of the nerve ending (axolemma). Administering the goniometer technique one can observe the appearance of a stalk-like structure connecting the two membranes. The basis of the stalk in the axolemma corresponds to the site of the stoma through which the core of the vesicle leaves the nerve ending. 3. The mechanism of the origin of small clear vesicles (diameter 500 Å approx.) near the axolemma of the neurosecretory terminal has not been elucidated. The authors did not observe equivalents of a compensatory endocytosis in the vicinity of granules released by exocytosis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 121 (1971), S. 153-170 
    ISSN: 1432-0878
    Keywords: Neutrophilic myelocyte ; Human bone marrow ; Secondary granulogenesis ; Phase contrast microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The developmental changes in the neutrophilic myelocyte from normal human bone marrow have been analyzed by means of phase contrast and electron microscopy. This developmental stage is characterized principally by the elaboration of secondary (specific) granules. In addition, there is a modest decrease in cell size, a decrease in the number and mean size of primary (azurophil) granules, a decrease in the number of polysomes, free ribosomes and mitochondria, a depletion of rough endoplasmic reticulum, an increase in cytoplasmic glycogen, an increase in chromatin aggregations and a loss of nucleoli, and the formation of a markedly indented nucleus. The myelocyte stage has been subdivided into three arbitrary phases based upon morphological and functional characteristics which relate to the onset, active production and cessation of secondary granulogenesis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 122 (1971), S. 1-14 
    ISSN: 1432-0878
    Keywords: Amnion ; Human amniotic plaques ; Fetal membranes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of amniotic and amniotic-plaque epithelia has been studied from normal term pregnancies. The columnar/cuboidal amniotic epithelial cells usually have apical or central nuclei, some free ribosomes, patches of granular endoplasmic reticulum, juxtanuclear Golgi complexes, rod-shaped mitochondria, lipid droplets and some glycogen granules. They have short, blunt microvilli which frequently branch and bathe in the amniotic fluid. The lateral plasma membranes enclose tortuous intercellular spaces which are always interrupted by variously folded processes and desmosomes. The epithelial cells rest on a basal lamina and exhibit highly folded basal processes. The amniotic epithelial cells are neither distinctly Golgi and fibrillar types nor “light” and “dark” in appearance. Amnion from near the umbilical cord contains many microscopic and several large plaques. Similar structures are not found on the reflected amnion. The microscopic plaques are whitish and translucent, whereas the large ones are opaque. The large plaques vary between 1–3 mm in diameter, and are over 15 cell layers thick. Each large plaque has a main central region and edges continuous with either the microscopic plaque or the simple amniotic epithelium. The main region shows four zones, namely, stratum basale, stratum spinosum, stratum granulosum and stratum corneum. Such zones are not distinct at the edges. The fine structure of basal cells compares with the amniotic epithelial cells, but the cells of spinosum and granulosum layers possess variable amounts of tonofibrils, keratohyalin granules, free ribosomes and other cytoplasmic organelles and inclusions. The corneum cells are keratinized and are frequently separated by intercellular spaces. They slough into the amniotic cavity singly or as a sheet, and contribute towards the composition of the amniotic fluid. The plaques are of amniotic origin, and are not formed by adhesion of either squamous cells or fetal skin cells (masses of keratinized squames). The present observations suggest that the occurrence of amniotic plaques is normal. The presence of plaques may not be necessarily associated with fetal abnormality. However, increase in numbers of plaques may be caused by conditions of fluid imbalance. The homology and significance of plaques in eutherian mammals have been discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    ISSN: 1432-0878
    Keywords: Neurones ; Lumbricus ; Monoamines ; Neurosecretion ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cerebral ganglion and the ventral nerve cord of Lumbricus terrestris have been studied with the electron microscope. The results are as follows: In the neuropile small granular vesicles (300 to 500 Å) occur in some varicose nerve fibres after fixation with potassium permanganate. This indicates the presence of noradrenaline. Sometimes only a few of the vesicles produce a positive reaction. After incubation with α-methyl-noradrenaline the numbers of nerve terminals with small granular vesicles greatly increase, indicating the presence of dopamine and/or 5-hydroxytryptamine. In this case the reaction is now complete. The number of small granular vesicles is largest in the terminal swellings. These findings are consistent with histofluorescence, chemical, and microspectrofluorometric analyses, which have demonstrated noradrenaline, dopamine, and 5-hydroxytryptamine in neurones in the central nervous system. Large granular vesicles (600 to 900 Å) are to be found in some perikarya, not identical with neurosecretory cell bodies. In this case the granular vesicles in the axon are smaller and fewer. This indicates a simultaneous proximo-distal transport and gradual decrease in size of the granular vesicles. The intraneuronal distribution of the vesicles is in agreement with the distribution of the fluorophores in the fluorescent neurones. Neurosecretory neurones are found most likely not to contain monoamines.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 126 (1972), S. 431-436 
    ISSN: 1432-0878
    Keywords: Golgi apparatus ; Granular endoplasmic reticulum ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Numerous morphological continuities between the cisternae of the convex face of the Golgi apparatus and the granular endoplasmic reticulum (GER) were observed in post-division amebae that had divided following enucleation and renucleation. Electron microscopic radioautography with the use of 3H-uridine as a tracer indicated that perhaps the Golgi apparatus is derived from the GER. The possibility of the connections between GER and Golgi apparatus facilitating transport of materials between the two is also discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 126 (1972), S. 466-482 
    ISSN: 1432-0878
    Keywords: Macrophages ; Microtubules ; Enamel organ ; Rat ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the enamel organ of rat incisors macrophages are present in the zone of matrix formation, the transitional zone, the enamel maturation and pigmentation zone. The macrophages accumulate adjacent to redifferentiating amelocytes in the transitional zone. The macrophages phagocytize fragments of disintegrating amelocytes. In addition to the well known complement of organelles the macrophages present an elaborated microtubular system, scattered, thick filaments, a cortical feltwork of thin filaments, and spherical nuclear bodies. The microtubules emanate from “attached” and free pericentriolar satellites and radiate aster-like towards the cell surface or into pseudopods or curve along the nuclear surface for long distances, often related to nuclear constrictions. It is suggested that the microtubular system plays a prominent role in directional movement of the macrophages. The cortical filaments, if contractile, may create the cytoplasmic flow necessary for the cell motility.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 127 (1972), S. 116-126 
    ISSN: 1432-0878
    Keywords: Cell junctions ; Nexus ; Osmotic effects ; Fixatives ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Speicheldrüsen von Mückenlarven (Chironomus Thummi) haben eine ausgedehnte interzelluläre Kommunikation. In elektronenmikroskopischen Bildern der Speicheldrüsen wurden zwei Arten von interzellulären Verbindungen gefunden, die für die Zellkopplung verantwortlich sein könnten: septate junctions und close membrane junctions. Da die räumliche Ausdehnung der septate junctions viel größer zu sein scheint als die der close junctions, wurden erstere als wahrscheinliche Kopplungsstrukturen angesehen. Es gibt jedoch Hinweise, daß die Strukturen, welche die Zellkopplung bewirken, sehr labil sind. Unter den Faktoren, die zu einer Unterbrechung der zellulären Kommunikationen führen können, sind auch osmotische Effekte. Um mögliche Einflüsse dieser Art auf die Ultrastruktur zu verhindern, wurden die Drüsen für die mikroskopische Inspektion in isoosmotischen Lösungen fixiert. Unter diesen Bedingungen lassen sich ausgedehnte Membrankontakte vom nexus-Typ zwischen den Drüsenzellen erkennen. Ihre Ausdehnung scheint ebenso groß zu sein wie die der septate junctions. Es besteht nach diesen Befunden die Möglichkeit, daß wie in anderen kommunizierenden Zellsystemen, so auch in Speicheldrüsen die interzelluläre Kommunikation durch nexus bewirkt wird.
    Notes: Summary Cells ofChironomus salivary glands communicate through intercellular connections of high permeability. Electron micrographs of salivary glands show two kinds of junctions between the membranes of adjacent cells, which may be responsible for cell coupling: septate junctions and close membrane junctions. A large fraction of lateral cell surfaces is occupied by septate junctions, while the area of close membrane junctions appears to be very small. Consequently septate junctions have been considered as likely sites for intercellular coupling. There are however some indications that intercellular communication is provided by structures which seem to be unstable. As osmotic effects are among the factors which can disrupt cellular communications, we have tried to eliminate possible effects of the fixing solutions on the ultrastructure of intercellular connections by using isoosmotic fixatives. Under these conditions large regions of close membrane junctions of the nexus kind have been observed to occur between gland cells. They are of similar size as septate junctions. It seems to be possible that as in other communicating cell systems nexus could be the sites for intercellular coupling of salivary gland cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    ISSN: 1432-0878
    Keywords: Synapses ; Crustacea ; Abdominal Ganglia ; Lateral glant fibers ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The abdominal ganglia of the crayfish Astacus pallipes contain numerous vertebrate-like synapses which are characterized by presynaptic vesicles, darkened pre- and post-synaptic membranes, cleft material, and post-synaptic “fuzz”. Such synapses occur throughout the ganglia but are most easily found dorsally, where the neuropile is relatively coarse. The neuropile is far from homogeneous. Regional variations in fiber size, in degree of profile tortuosity, and in kind, magnitude, and distribution of vesicular content result in conspicuous textural variations. The structural polarity of synapses between the lateral giant fibers and other neurons is consistent with known physiological polarity and, hence, validates our criteria for recognition of synapses within the ganglion.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 128 (1972), S. 42-57 
    ISSN: 1432-0878
    Keywords: Microglia ; Pericytes ; Cerebral cortex (cat) ; Transformation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Capillaries, pericytes and microglial cells in layer I of the cerebral cortex of normal adult cats have been studied with electron microscopy. The data obtained in this study show that pericytes are cells which are able to transform themselves into microglial cells by virtue of an activation process in which the astrocytic neuroglia appears to play a decisive role. By virtue of its structure, its mesodermic origin and its function the microglia has to be distinguished clearly from the astrocytic neuroglia and the oligodendroglia.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 128 (1972), S. 100-114 
    ISSN: 1432-0878
    Keywords: Connective tissue ; Gastropoda ; Globular cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Blasenzellen stellen ein typisches Zellelement im Bindegewebe der Gastropoden dar. Licht- und elektronenmikroskopische Untersuchungen an Cepaea nemoralis haben gezeigt, daß der größte Teil einer Blasenzelle mit einer veränderlichen Glykogenmenge angefüllt ist. Diese zentrale Glykogenansammlung verdrängt das Zytoplasma mit seinen Organellen auf den peripheren Bereich der Zelle einschließlich der Zellausläufer und einen schmalen Saum um den Zellkern. Das wichtigste Identifizierungs-merkmal der Blasenzelle ist eine sehr spezialisierte — hier als Spaltenapparat bezeichnete — Oberflächendifferenzierung. Die Auswertung von Serienschnitten hat gezeigt, daß diese Oberflächenstruktur durch eine zum Teil verzweigte Invagination des extrazellulären Raumes gebildet wird, die wiederum von der Blasenzelle durch eine mäanderförmig unterbrochene Platte abgedeckt ist. Zwischen dem Spaltenapparat der Blasenzellen und dem Reusenapparat der Podozyten der Niere scheint eine Ähnlichkeit zu bestehen.
    Notes: Summary The globular cells are typical elements of the connective tissue of Gastropods. Light- and electronmicroscopic investigations of Cepaea nemoralis have shown, that these cells are filled with variable contents of glycogen, accumulated in the centre of the cell. This crowds the cytoplasm and the cell organelles into the peripheral area, including the cell processes and a narrow band surrounding the nucleus. The typical element of the globular cell is a special differentiation of the cell surface, the so-called “Spaltenapparat”. The three-dimensional organisation of the “Spaltenapparat” has been analysed by serial ultrathin sections. The reconstruction shows, that the “Spaltenapparat” consists of numerous branched invaginations of the extracellular space covered by very small, winding cell processes; there are tiny clefts between them. There appears to be some similarity between the “Spaltenapparat” of the globular cells and the pedicels of the podocytes of the renal glomerulus.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 128 (1972), S. 135-138 
    ISSN: 1432-0878
    Keywords: Spinal cord ; Mouse ; Myelinated neuronal soma ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im Thorakalmark (Hinterhornbereich) einer Wildmaus wurde ein kleines Nervenzellperikaryon beobachtet, das vollständig von einer Markscheide umhüllt war. Die Zahl der Markscheidenlamellen variierte zwischen 7 und 12. An einer Stelle konnte ein sogenanntes inneres Mesoperikaryon nachgewiesen werden. Die Bedeutung dieses zufällig erhobenen Befundes ist vorerst noch offen.
    Notes: Summary In the thoracic cord (posterior horn region) of a wild mouse, we have observed a small nerve cell soma completely enveloped by a myelin sheath. The number of myelin lamellae varied between 7 and 12. In one place, the existence of an inner ‘mesoperikaryon’ could also be shown. The significance of this fortuitous finding has not yet been explained.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 126 (1972), S. 53-74 
    ISSN: 1432-0878
    Keywords: Oogenesis ; Rhesus monkey ; Meiotic chromosomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ovaries of foetal and neonatal rhesus monkeys have been examined with the electron microscope. The fine structure of the germ cells (oogonia; oocytes at the preleptotene, leptotene, zygotene, pachytene and diplotene stages of meiotic prophase) closely resembles that of corresponding human cells. Stages in spontaneous atresia are also described. Cytoplasmic organelles in oogonia are sparse and are grouped mainly at one pole of the nucleus, but become dispersed and more abundant as oogenesis proceeds. The nuclei of oogonia contain a random fibrillar matrix which becomes organized into threads at pre-leptotene. At leptotene these chromosomal threads each contain a dense axial “core”; during zygotene they become loosely paired in a “bouquet” arrangement and at pachytene the bivalents contain synaptinemal complexes. “Single” cores reappear at diplotene, surrounded by a complex fibrillar sheath organized into lateral projections and loops with associated granules: such chromosomes resemble those in human primordial oocytes although they are more diffuse. These findings support the view that at the diplotene stage mammalian oocytes contain chromosomes of the lampbrush type. Observations on the monkey are compared with those on other species, and the ways in which chromosomal organization may influence the radiosensitivity of oocytes is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 129 (1972), S. 1-10 
    ISSN: 1432-0878
    Keywords: Spermatogonia ; Fish ; Annulate lamellae ; Chromatoid bodies ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Observations on annulate lamellae and chromatoid bodies in spermatogonia of the cyprinid fish Pimephales notatus have revealed several commonly occurring features heretofore unreported: These include (a) the presence of annulate lamellae in close association with chromatoid bodies; (b) the existence of a chromatoid “band” or “shell” between the nuclear envelope and some chromatoid bodies with connections among them; (c) the presence of annulate pore complexes in the absence of well developed membrane envelopes as well as in association with such envelopes; (d) the presence of material just outside the nucleus and contiguous with nuclear pores which is of a similar density and texture to that of the chromatoid bands and chromatoid bodies; (e) filamentous material between the cytoplasmic sides of nuclear pores and the chromatoid “band”, bridging a distance of approximately 1000 Å and similar threads extending a like distance between chromatoid bodies (and bands) and annulate lamellae associated with them; and (f) mitochondria closely arranged about some chromatoid bodies.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 127 (1972), S. 127-148 
    ISSN: 1432-0878
    Keywords: Nuclear envelope ; Amphibian oocytes ; Nuclear pore complex ; Chemical nature ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to investigate the chemical composition of the nuclear pore complexes isolated nuclei from matureXenopus laevis oocytes were manually fractioned into nucleoplasmic aggregates and the nuclear envelopes. The whole isolation procedure takes no more than 60–90 sec, and the pore complexes of the isolated envelopes are well preserved as demonstrated by electron microscopy. Minor nucleoplasmic and cytoplasmic contaminations associated with the isolated nuclear envelopes were determined with electron microscopic morphometry and were found to be quantitatively negligible as far as their mass and nucleic acid content is concerned. The RNA content of the fractions was determined by direct phosphorus analysis after differential alkaline hydrolysis. Approximately 9% of the total nuclear RNA of the matureXenopus egg was found to be attached to the nuclear envelope. The nonmembranous elements of one pore complex contain 0.41×10−16 g RNA. This value agrees well with the content estimated from morphometric data. The RNA package density in the pore complexes (270×10−15 g/μ3) is compared with the nucleolar, nucleoplasmic and cytoplasmic RNA concentration and is discussed in context with the importance of the pore complexes for the nucleo-cytoplasmic transport of RNA-containing macromolecules. Additionally, the results of the chemical analyses as well as of the3H-actinomycin D autoradiography and of the nucleoprotein staining method of Bernhard (1969) speak against the occurence of considerable amounts of DNA in the nuclear pore complex structures.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 127 (1972), S. 50-86 
    ISSN: 1432-0878
    Keywords: Salivary glands ; Drosophila, larval ; Differentiation ; Involution ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Entwicklung bzw. Differenzierung der larvalen Speicheldrüse vonDrosophila melanogaster wurde an genau datierten Altersstadien aus dem III. Larvenstadium, der Vorpuppe und der Puppe mit lichtmikroskopischen und elektronenmikroskopischen Methoden untersucht. Zur Vermeidung großer Streuung im physiologischen Alter der Tiere wurde eine Kulturmethode entwickelt, die es erlaubt, die Häutungen zu beobachten und zur Altersbestimmung heranzuziehen. Folgende Ergebnisse wurden erzielt: 1. Die Speicheldrüse besteht bis zur Mitte des III. Larvenstadiums morphologisch aus einem einheitlichen Zelltypus, der sehr kleine Sekretgrana (∅ 0,3 μm) bildet. Diese sammeln sich am Zellapex. Die Vermutung liegt nahe, daß es sich um ein Verdauungssekret handelt.In der 2. Hälfte des III. Larvenstadiums differenzieren sich drei Zelltypen, die hier Corpuszellen, Übergangszellen und Halszellen genannt werden. Dabei ist ein Differenzierungsgradient von distal nach proximal zu beobachten. Die distal gelegenenCorpuszellen stellen die Bildung des Verdauungssekretes in der 2. Hälfte des III. Larvenstadiums ein und bilden stattdessen ein Klebesekret. Dieses Sekret wird in Form großer Grana (∅ bis zu 10 μm) zunächst in den Zellen gespeichert und kurz vor der Pupariumbildung ins Lumen der Drüse abgegeben. Kurz nach der Pupariumbildung wird das Klebesekret aus dem Körper entlassen und dient dazu, die Tönnchenpuppe an einem trockenen Substrat anzuheften. Das Klebesekret ist PAS-positiv. Wahrscheinlich handelt es sich um ein Mucoproteid. Während des Vorpuppenstadiums bilden sich in den Corpuszellen große Vakuolen, die auf Grund der elektronenmikroskopischen Befunde als Ausdruck einer weiteren Sekretionsphase und nicht als beginnende Degeneration gedeutet werden. Die mögliche Bedeutung dieses Sekretes wird diskutiert. DieÜbergangszellen liegen zwischen den Corpuszellen und den Halszellen. Sie bilden ebenfalls Klebesekret, jedoch mit zeitlicher Verzögerung. Kurz vor der Pupariumbildung sind sie wie die Corpuszellen mit ausgereiften Klebesekretgrana beladen und von diesen nicht mehr zu unterscheiden. Die proximal gelegenenHalszellen bilden kein Klebesekret, sondern setzen die Bildung des Verdauungssekretes in der 2. Hälfte des III. Larvenstadiums fort. Während des Vorpuppenstadiums bilden sich in den Halszellen nicht die großen Vakuolen wie in den Corpuszellen. 2. Die Involution der larvalen Speicheldrüse erfolgt nach der Puppenhäutung durch Autolyseprozesse, die am distalen Ende der Drüse beginnen und innerhalb 1 Std alle Zellen mit Ausnahme der Imaginalanlage erfassen. 3. Die in dieser Untersuchung erhobenen entwicklungsgeschichtlichen Befunde anDrosophila melanogaster werden mit Beobachtungen anDrosophila virilis, D. robusta undD. hydei verglichen. Dabei wird aufgezeigt, daß die Entwicklung der larvalen Speicheldrüsen von verschiedenenDrosophila-Arten enge Parallelen aufweist. Die bisher bekannten Zusammenhänge zwischen Stoffwechselaktivitäten im Zytoplasma und Genaktivitäten (Puffmuster) an den Riesenchromosomen dieser Zellen werden diskutiert.
    Notes: Summary The development and differentiation of the larval salivary glands ofDrosophila melanogaster have been investigated with light and electron microscopical methods. The organ has been dissected out of exactly dated stages of the III. instar larva, the prepupa and the early pupa. In order to avoid great variations in the physiological age of the animals a culture method has been developed, enabling the larval molts to be observed and used for identification of the age. The results are as follows: 1. The salivary gland of the early larva up to the middle of the III. instar period is a homogenous sack consisting of one sort of cells, in which very small secretion granules (∅ 0,3 μm) are synthesized. These secretion granules concentrate near the cellular apex. They are supposed to contain digestion enzymes. 2. In the second half of the III. larval instar period three cell types are differentiated, which are called corpus cells, transitional cells and collum cells. A gradient of differentiation from distal to proximal can be observed. 3. Thecorpus cells, located at the distal part of the gland, stop the production of digestion enzymes in the second half of the III. larval instar period and begin to synthesize a cement substance. This cement first is stored in grana (∅ up to 10 μm) inside the corpus cells. Shortly before puparium formation it is extruded into the lumen of the gland. Shortly after puparium formation it is expectorated out of the mouth, runs along the body wall and affixes the puparium to the substrate. The cement is PAS-positive, probably being a mucoproteid. In the corpus cells large vacuoles are formed during the prepupal instar period. On the basis of these electron microscopical results the vacuoles are interpreted to represent another form of a secretory product and not an equivalent of beginning degeneration. The possible function of this substance is discussed. 4. Thetransitional cells are located between the corpus cells and the collum cells. They also synthesize cement at a delayed rate, through shortly before puparium formation they are filled with cement like the corpus cells and cannot be distinguished from the latter. Thecollum cells form the most proximal part of the salivary gland. They do not produce cement but continue to synthesize digestion enzyme granules in the second half of the III. instar period. The large secretion vacuoles, found in the corpus cells during the prepupal instar period, are not synthesized in the collum cells. 5. The involution of the larval salivary gland begins after pupation and is indicated by autolytic processes, which begin at the distal end of the gland. One hour later all cells exept the imaginalanlage show signs of degeneration. 6. The course of development of the salivary glands investigated in the present study inDrosophila melanogaster is compared with similar investigations onDrosophila virilis, robusta andhydei. It is pointed out that the development of the larval salivary gland in different species ofDrosophila shows close parallels. The relationships between metabolic activities in the cytoplasm and gene physiological activities (pattern of puffs) on the giant chromosomes, as known so far, are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 130 (1972), S. 70-92 
    ISSN: 1432-0878
    Keywords: Oocytes ; Different types ; Dinophilus gyrociliatus ; Cytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Dinophilus gyrociliatus bildet zwei Oocytentypen, einen größeren, aus dem ♀♀ hervorgehen (♀-Oocyte) und einen kleineren, der sich zu ♂♂ entwickelt (♂-Oocyte). Diese beiden Oocytentypen sind von frühen Stadien der Vitellogenese an durch ihr unterschiedliches Größenwachstum zu unterscheiden. Da bei Oogonien und prävitellogenen Oocyten keine zwei unterschiedlichen Zelltypen festzustellen sind, muß man annehmen, daß die Differenzierung in ♂- und ♀-Oocyten in einem zwischen der Prävitellogenese- und der Vitellogenesephase gelegenen Übergangsstadium beginnt. Während der Prävitellogenesephase finden Zellverschmelzungen statt, aber es konnten keine Beziehungen zwischen der Fusion von Oocyten und der späteren Differenzierung nachgewiesen werden. Die ♂-Oocyte beginnt schon auf einem frühen Stadium der Vitellogenese mit der Produktion von Mucopolysaccharid-Granula, die ♀-Oocyte erst später. Diese Granula bilden nach der Ablage der Eier die Ei- oder die Kokonhülle. Die ♀-Oocyte bildet größere Proteindottergranula als die kleinere ♂-Oocyte. Eine Trennung zweier Zellsorten nach Granulagrößen läßt sich schon auf dem Übergangsstadium durchführen. Der absolute RNS-Gehalt der reifen ♀-Oocyte liegt wesentlich über dem der ♂-Oocyte; dagegen ist die Konzentration der RNS in der ♂-Oocyte höher. Die RNS-Synthese verläuft in beiden Oocytentypen parallel zur Volumenzunahme und dauert bis zum Ende der Vitellogenesephase.
    Notes: Summary Dinophilus gyrociliatus produces two types of oocytes, a big, female producing “♀-oocyte”, and a smaller, male-producing “♂-oocyte”. They may be distinguished by their different volume from the beginning of the vitellogenic phase. Neither oogonia nor previtellogenic oocytes show two types of cells, and the beginning of differentiation in ♀-oocytes and ♂-oocytes has to be located in a connecting stage after the previtellogenic and before the vitellogenic phase. On previtellogenic stages the cells fuse and form bigger ones, but there is no connection to be found with the differentiation of the egg cells. The ♂-oocyte starts the production of mucopolysaccharid granules at an early vitellogenic stage; the ♀-oocyte does so only at later stages. These granules form the egg capsule after the eggs have been laid. The ♀-oocyte contains bigger protein yolk granules than the smaller ♂-oocyte. Already on the connecting stage it is possible to distinguish two groups of cells by the size of their granules. The ribonucleic acid content in the ♀-oocyte exceeds greatly that of the ♂-oocyte. The RNA-concentration, however, is higher in the latter one. During the vitellogenic stages the rate of RNA-synthesis in either type of oocytes parallels the increase in cell volume, the synthesis lasting up to the end of the vitellogenic phase.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 131 (1972), S. 417-427 
    ISSN: 1432-0878
    Keywords: Lymphatic vessels ; Lung ; Centrioles ; Filaments ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An electron microscopic study of the pulmonary lymphatic collecting channels and their valves in the rabbit revealed that the endothelial cells generally contain two centrioles which are almost invariably associated with one to several striated bundles of filaments. The structure of the centrioles corresponds well with that in other cell types. The filaments however were present only in endothelial cells and not in the perilymphatic connective tissue cells. The bundles consist of 2 to 6 filaments of about 40 Å diamenter and show a cross banding with a periodicity of 600 to 900 Å. They are attached at both ends or in the middle of the centriole. Their function is unknown, but they might be vestigial rootlets of rudimentary cilia of lymphatic endothelial cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 132 (1972), S. 365-380 
    ISSN: 1432-0878
    Keywords: Golgi apparatus ; Membranes ; Cross-bridges ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron opaque cross-bridge structures span the inter- and intracisternal spaces and provide membrane-to-membrane connections between adjacent cisternae of dictyosomes of pollen tubes ofClivia andLilium. Additionally, the classic intercisternal rods, characteristic of intercisternal regions near the maturing face of dictyosomes, are connected with the adjacent membranes through similar cross-bridge elements. We suggest that these structural links are responsible for maintaining the flattened appearance of the central parts of Golgi apparatus cisternac as well as for the coherence of cisternae within the stack. Observations on other plant (e.g. microsporocytes ofCanna) and animal cells (e.g. rodent liver and hepatoma cells, newt spermatocytes) show that such an array of membrane cross-links is a universal feature of Golgi apparatus architecture. The cross-bridges appear as part of the complex “zone of exclusion” which surrounds dictyosomes, entire Golgi apparatus and Golgi apparatus equivalents in a variety of cell types.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 130 (1972), S. 243-248 
    ISSN: 1432-0878
    Keywords: Blood vessels ; Chicken embryo ; Multivesicular structures ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung In verschiedenen Arten von Gefäß- und Mesenchymzellen in Allantois und Dottersack des Hühnchens wurden regelmäßig sog. „multivesicular structures“ beobachtet, die aus intrazellulären Aggregaten von Vesikeln (Durchmesser ca.: 800 Å) und/oder Vakuolen (Durchmesser bis 5000 Å) bestehen. Ähnliche Befunde anderer Autoren und die eigenen Ergebnisse sprechen dafür, daß es sich um das Substrat einer weitverbreiteten Zellreaktion handelt, die u.a. das morphologische Äquivalent der Sequestrierung eines z.B. im Zuge der Zelldifferenzierung überflüssig gewordenen Zytoplasmaanteils darstellt.
    Notes: Summary In the endothelial, the media and mesenchymal cells of the vessels in the chicken's allantoic and vitelline membranes “multivesicular structure” regularly occur. They consist of aggregated vesicles and/or vacuoles (diameters ranging from 800 Å to 5000 Å) and seem to present a rather common and widespread cellular reaction, that might serve as a mechanism to sequester those parts of the cytoplasm which became superfluous e.g. during cell differentiation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 130 (1972), S. 338-350 
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Salmon ; Gonad maturation ; Cell types ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the various hormone-producing cell types (with the exclusion of the prolactin cells) in the pituitary gland (pars distalis) of migratory sockeye salmon is described. All fish were in an advanced stage of sexual maturation. In the proximal pars distalis five cell types were distinguished: growth hormone cells, ACTH cells, gonadotrops, “vesicular cells”, and “chromophobe cells”. Gonadotrops were also found throughout the rostral pars distalis. A conspicuous feature of the gonadotrops was the presence of two kinds of secretory inclusions: small electron-dense granules (200–375 mμ) and large, relatively electron-translucent globules (400–2 000 mμ). The large vesicular cells, so called because of their conspicuous vesicular endoplasmic reticulum, were numerous and often appeared to contain some small granules. It is argued that they may represent a second type of gonadotropic cell, which, in earlier stages of gonad development, contains many granules but becomes largely degranulated near the time of reproduction when the other gonadotrops (“globular gonadotrops”) abound. The chromophobes, which were smaller and far less abundant than the vesicular cells, also appeared to contain small granules (120–280 mμ). They are probably thyrotrops.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 131 (1972), S. 347-370 
    ISSN: 1432-0878
    Keywords: Spermatozoon ; Pleurodeles ; Acrosome ; Differentiation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'origine et la morphogenèse des différents éléments de l'acrosome du spermatozoīde dePleurodeles waltlii ont été suivies et décrites depuis le tout début de la spermiogenèse. La formation de la vésicule acrosomienne et son évolution en une coiffe acrosomienne se fait selon le schéma classique. Son extrémité apicale se différencie tardivement en un bouton terminal et un crochet. Les trois parties de la coiffe diffèrent dans leur composition et leur structure fine. Les volumineux et complexes éléments situés sous la coiffe acrosomienne: axe, baguette puis manchon périphérique et manchon moyen, sont dépourvus de polysaccharides. Leur origine est envisagées. Ils sont comparés aux éléments situés dans l'espace sous-acrosomien des spermatozoīdes des autres vertébrés.
    Notes: Summary The origin and the morphogenesis of the acrosome different parts ofPleurodeles spermatozoon, have been investigated and described from the early beginning spermiogenesis process. The acrosomal vesicle and acrosomal cap formation take place according to the classical scheme. The acrosomal anterior tip cap late differentiate in a blunt terminal knob and a hook. The three cap parts differ in their composition and fine structure. The large and complicated structure stretching under the acrosomal cap: axis, peripheral muff and middle muff, are devoided of polysaccharides; their origin is discussed. They are compared with the subacrosomal components lying in the other vertebrates spermatozoon subacrosomal space.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 135 (1972), S. 211-228 
    ISSN: 1432-0878
    Keywords: Osteoclasts ; Rats ; Bone resorption ; Lysosomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Osteoclasts in metaphyses from young rats were systematically sectioned at different levels. Two types of osteoclasts were recognized. One type had no ruffled border while the other, and predominant type contained a ruffled border in a part of its length; some of the latter contained two ruffled borders. The closest contact between osteoclast and bone occurred at the level of the ruffled border and this bone under the border showed characteristic changes indicative of resorption. In some osteoclasts the ruffled border consisted of numerous slender cytoplasmic projections separated by very narrow spaces or channels while in other osteoclasts it was more open. The ruffled border was commonly surrounded by a transitional zone containing numerous thin filaments. The osteoclast usually had its greatest dimension at the level of the ruffled border and the cytoplasm here contained many bodies and vacuoles but a sparse endoplasmic reticulum. Away from the level of the ruffled border the cytoplasmic vacuoles and bodies were fewer while the endoplasmic reticulum was often more pronounced. Parts of the osteoclasts were usually situated close to a vessel. It is suggested that there is a correlation between the development of the ruffled border and the degree of bone resorption and that osteoclasts without a ruffled border are, at least temporarily, inactive with respect to bone resorption. The numerous cytoplasmic bodies, interpreted as lysosomes, are presumed to be important in the resorption process. The closely adjacent positioning of osteoclasts and vessels may facilitate the transport of resorption products to the blood.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 133 (1972), S. 82-102 
    ISSN: 1432-0878
    Keywords: Echinoidea ; Colour change ; Chromatophores ; Amoeboid movement ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Für den physiologischen Farbwechsel bei Vertebraten und Evertebraten gilt die Vorstellung, daß eine Pigmentbewegung innerhalb einer formkonstanten Zelle stattfindet. Am Seeigel Centrostephanus longispinus wird nun der Nachweis einer amoeboiden Bewegung von Pigmentzellen geführt: Die Epidermis von Centrostephanus enthält große braune Chromatophoren, die bei Belichtung eine Pigmentdispersion, bei Verdunkelung eine Konzentration des Pigments zeigen. Die Chromatophoren sind außerordentlich stark verzweigte Zellen, deren Arme dicht mit Pigmentgrana erfüllt sind. Im geballten Zustand ist die allgemeine Zellform mehr oder weniger ovoid, wobei die Zellarme eingezogen und dicht um die Zellmitte angeordnet sind. Dispersion des Pigments wird hervorgerufen durch Ausstrecken der pigmentierten Zellarme in den Interzellularraum des umgebenden Gewebes. Innerhalb der Zelle werden filamentöse Elemente nachgewiesen, die vermutlich für die Zellbeweglichkeit verantwortlich sind. — Ferner wird der zelluläre Aufbau des Integuments beschrieben.
    Notes: Summary Rapid colour changes in vertebrate and invertebrate species are considered to be due to movement of pigment granules within pigment cells of constant shape. Evidence is presented in this study to show that an amoeboid movement of chromatophores occurs in the epidermis of the Echinoderm Centrostephanus longispinus. The epidermis in this species contains large brown chromatophores, which display a dispersion of pigment on illumination and its concentration on darkening. The chromatophores are extensively branched cells, and their branches are densely packed with pigment granules. In the state of pigment concentration, the shape of the cell is more or less ovoid, and the cell branches are drawn in and closely arranged around the cell centre. Dispersion is attained by a stretching out of the pigmented cell branches into the intercellular spaces of the surrounding tissue. Within the cell, filamentous elements, which may be functional in the motility of the pigment cell, can be demonstrated.—Additionally the cellular composition of the integument is described.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 135 (1972), S. 439-448 
    ISSN: 1432-0878
    Keywords: Neuromuscular junction ; Triturus ; Colchicine ; Axoplasmic flow ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Repeated injections of colchicine into the forearms of normal adult newts led to the disappearance of microtubules within some nerves and a concomitant loss of specialized morphological features at the neuromuscular junction. Within 2 weeks, the postsynaptic folds decreased in height and number, became flattened and eventually disappeared. In addition, nerve terminals in drug-treated animals became separated from the muscle surface and were highly congested with masses of synaptic vesicles. The present findings show that colchicine has an effect on the structural integrity of the neuromuscular junction. These effects could be direct; secondary to retraction of the nerve from the muscle surface; or the result of interference with the proper transport and/or release of neurotrophic substances.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 135 (1972), S. 449-459 
    ISSN: 1432-0878
    Keywords: Insect brain ; Neurons ; Glia ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the neural sheath, glial cells and nerve cells in the brain of adult male houseflies is described. The neural sheath is composed of neural lamella and perineurium. The neural lamella consists of an external lamina and collagen-like fibrils which are embedded in an amorphous matrix. The perineurial cells form a continuous layer around the brain. On their inner surface, perineurial cells form junctional complexes with glial cell processes. A cortical cellular layer composed of neurons and glial cells surrounds the centrally located neuropil. Three types of glial cells are identified. Glial cells differ in size and in relative development and distribution of organelles. Thin processes of glioplasm completely surround the cell bodies of the neurons. Five types of neurons are described. Most of the neurons are monopolar, a few are bipolar.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 135 (1972), S. 461-471 
    ISSN: 1432-0878
    Keywords: Centriole assembly ; Basal bodies ; Ciliogenesis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopy of 16 to 18 day old chick tracheas revealed that procentrioles are present near the basal ends of the recently matured centrioles and basal bodies of both ciliating and ciliated cells. Cylinders 0.1 μ in outside diameter in which densely staining walls and a central axial filament can often be detected, are present between the mature centrioles and these procentrioles. These cylinders although somewhat shorter are morphologically similar to those found earlier in the same cells in the center of procentriole clusters. So far, only one procentriole has been found in association with each cylinder and only one cylinder in association with each mature centriole or basal body. Procentrioles up to 0.18 μ in length including some with singlet microtubules in their walls have been detected. Serial sectioning indicated that in some cells up to 8% of the mature centrioles and basal bodies were associated with a cylinder and a distinct procentriole. If these procentrioles were to mature they could provide additional basal bodies for cilia after the initial wave of centriole assembly and maturation has been completed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 136 (1973), S. 85-96 
    ISSN: 1432-0878
    Keywords: Liver ; Lampetra ; Physiological biliary atresia ; Electron microscopy ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A morphologic and histochemical study was carried out on the liver of larval and adult lampreys at the optical and electron microscopic level. In the larva the liver is composed of blind ending single cell thick tubules of hepatocytes. The tubular lumina provided with microvilli are morphologically comparable with the canalicular lumens of the higher species of animals. The cytoplasm of the hepatocytes contains numerous inclusions with heterogeneous appearance and crystalline material. The biliary system is composed of numerous bile ductules and ducts. In the adult lamprey, the biliary system has disappeared. The hepatocytes loose their tubular arrangement and the characteristic differentiation of their biliary pole. In contrast to previous reports in the literature the presence of bile pigment in the adult lamprey liver could not be demonstrated with any histochemical technique.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    ISSN: 1432-0878
    Keywords: Interstitial cells, genesis ; Hen's ovary ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Für die Zwischenzellen des Hühnerovars gibt es embryonal und post-embryonal bindegewebige und epitheliale Quellen. Die bindegewebigen Mutterzellen sind Mesenchymzellen und Fibrozyten, die epithelialen Mutterzellen sind Wandepithelzellen der Markstranglakunen und Epoophorontubuli. Kriterien zur Unterscheidung dieser vierfachen Abstammungsmöglichkeiten der Zwischenzellen werden angegeben.
    Notes: Summary The interstitial cells of the hen's ovary have two sources: connective tissue mother cells, which are mesenchymal cells or fibrocytes, and epithelial mother cells, which are wall epithelial cells of the medullary cord lacunae or of the tubuli of the epophoron. Criteria are provided for differentiating this fourfold genesis of the interstitial cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 139 (1973), S. 101-148 
    ISSN: 1432-0878
    Keywords: Infundibulum ; Rat ; Neuro-glial synapses ; Neuro-Vascular contacts ; Corticotropin-Releasing Factor ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Die Gefäßfortsätze von ependymalen und subependymalen Zellen bilden in der subependymalen Zone und in der Zona interna des Ratteninfundibulum mit Nervenfasern kompakte neuro-gliöse Faserbündel, die sich in der Zona externa aufzweigen. 2. In allen Zonen des Infundibulum kommen zwischen den Nervenfasern und den Gefäßfortsätzen zahlreiche neuro-gliöse Synapsen vor. In den Gefäßfortsätzen fällt die hohe Zahl an Mikrotubuli sowie die zahlreichen, vielgestaltigen Einschlüsse auf. 3. In der subependymalen Zone sind die Interzellularspalten an bestimmten Stellen außerordentlich weit. Sie haben eine kanalartige Beschaffenheit und enthalten feine Bündel von Nervenfasern. 4. Von den lateralen Anteilen des Infundibulum her erreichen Dendriten von Ganglienzellen des Nucleus infundibularis die Mitte des Infundibulum. In dieser Region sind axodendritische Synapsen anzutreffen. 5. Morphometrische Analysen der Nervenfaserendigungen der Zona externa von Normaltieren zeigen, daß die prozentuale Verteilung der nach Granulagröße differenzierten Nervenfaserklassen für Mitte und Seite der Zona externa etwa gleich ist. Zwischen der Größe der Elementargranula und der Anschnittfläche der zugehörigen Nervenfasern besteht eine direkte Beziehung. 6. Die Nervenfaserendigungen erreichen die Basalmembran des perikapillären Raumes fast ausschließlich im Bereich von gefäßwärts gerichteten Vorwölbungen der Zona externa. Das Ausmaß, in dem Nervenfasern im Vergleich zu den Gefäßfortsätzen von Ependymund Gliazellen den perivaskulären Raum erreichen, ist medial weitaus größer als lateral. 7. Bei bilateral adrenalektomierten Ratten nimmt in bestimmten, vorwiegend lateral gelegenen Nervenfasern die Zahl und Größe der Elementargranula in Abhängigkeit von der Überlebensdauer zu. Dies dürfte auf eine verstärkte Synthese und Speicherung von Corticotropin-Releasing Factor in diesen Nervenfasern zurückzuführen sein. Gegenüber dem Normalbefund ist die neurohämale Kontaktfläche erheblich vergrößert. Der perivaskuläre Raum enthält zerfallene Nervenfaserteile, die durch Bindegewebszellen phagocytiert werden. Diese Veränderungen dürften durch eine unter Versuchsbedingungen verstärkte Wachstumstendenz der Nervenfasern in Richtung auf die Blutgefäße und durch eine Abschnürung der Nerven-faserendigungen ausgelöst werden.
    Notes: Summary 1. In the subependymal and internal zones of the rat median eminence nerve fibres and vascular processes of ependymal and subependymal cells form neuro-glial bundles. They branch in the external zone. 2. In all these three zones of the infundibulum numerous neuro-glial synapses are found between nerve fibres and vascular processes of glial cells. The vascular processes contain a high number of microtubules as well as polymorphous granular inclusions. 3. In certain regions of the subependymal layer the intercellular spaces are enlarged. They form channel-like spaces containing small bundles of delicate nerve fibres. 4. Nerve cells of the infundibular nucleus located in the lateral parts of the infundibulum send dendrites to the medial parts of the infundibulum. In this area axo-dendritic synapses are found. 5. For morphometric analysis, the nerve fibres of the external zone were classified according to the diameter of their granules. It is shown that in the different regions of the external zone the distribution of the various types of nerve fibre is similar. Moreover it can be seen that a direct correlation exists between the size of the sectional plane of a given nerve fibre and the size of the granules it comprises. 6. Nerve fibre endings abutting on the basement membrane of the pericapillary space are mostly found in bulb-like protrusions of the external zone. The extent to which nerve fibres reach the perivascular space—as compared with the vascular processes of ependymal and glial cells—is higher in the medial than in the lateral parts of the infundibulum. 7. In bilaterally adrenalectomized rats the number and diameter of elementary granules increases in nerve fibres located laterally. This increase is directly related to the survival time and may be due to an enhanced synthesis and storage of Corticotropin-Releasing Factor in these nerve fibres. Compared with the findings in untreated animals the neurohemal contact area is significantly enlarged. The perivascular space contains degenerating nerve fibres which are undergoing phagocytosis by connective tissue cells. It is assumed that these alterations are due to the increased growth of nerve fibres towards the vessels of the “Mantelplexus”, and that, following adrenalectomy, this excessive growth leads to a pinching off of nerve fibres.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 138 (1973), S. 75-83 
    ISSN: 1432-0878
    Keywords: Invertebrate ganglia ; Spisula solida ; ynapses ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An examination using the electron microscope was carried out on the visceral ganglion of the marine bivalve mollusc Spisula solida. A range of fixation, block staining and section staining technique was used to study the structure of chemical synapses. Phosphotungstic acid employed as a block stain specifically stained pre- and post-synaptic structures associated with the membrane at synapses as well as one class of granular vesicle. The specialised contacts were however shown to be rare and in many parts completely absent. Many axons, containing several types of vesicle, were shown to be varicose and it is proposed that they may function in a similar way to the unspecialised varicose terminals of vertebrate autonomic neurons. The role of membrane specialisations in intercellular adhesion is discussed. This study concludes that many synapses may be morphologically unidentified using present criteria.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 138 (1973), S. 171-186 
    ISSN: 1432-0878
    Keywords: Tooth germs ; Organ culture ; Differentiation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Tooth germs from foetal rats of 17 days post-insemination were maintained in vitro for 12 days. Odontoblasts and ameloblasts differentiated and secreted their respective matrices in which mineralization occurred. The ultrastructure of the cells was qualitatively similar to that observed in normal development. Odontoblasts contained more lysosome-like bodies and were found to degenerate in some sites. Mantle dentine was formed but few von Korff fibres were observed. Calcospherites were rarely seen and the mineralizing front of dentine was predominantly linear, associated with numerous small early foci of mineral formation. Enamel showed prism formation associated with the Tomes' process of the ameloblast but some local disturbances in the pattern of enamel formation were observed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 138 (1973), S. 273-282 
    ISSN: 1432-0878
    Keywords: Nucleoli ; Type ; Influence of histone ; Tissue culture ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The frequency of various types of nucleoli was investigated in tissue cultures of human embryonal lung and HeLa cells cultured in the presence of calf thymus histone. The nucleolar morphology and the frequency of various nucleolar types were dependent on the concentration of histone in the tissue cultures of the human embryonal lung cells. HeLa cells required longer cultivation with histone to manifest some effect on nucleoli. In both cases, the observed nucleolar changes suggest the depression of nucleolar RNA synthesis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 138 (1973), S. 261-272 
    ISSN: 1432-0878
    Keywords: Extrarenal blood vessels ; Rat ; Adrenergic nerves ; Fluorescence microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The adrenergic innervation of the extrarenal blood vessels of the rat left kidney was investigated by fluorescence histochemistry and by electron microscopy. The trunk of the renal artery proximal to the aorta is elastic and appears to be very sparsely innervated. In contrast, near the kidney the renal artery—which divides into 3 to 4 large branches of the muscular type possesses a dense adrenergic innervation. The adrenergic terminal axons are situated in the adventitia close to the external elastic lamella, but only rarely in close contact with smooth muscle cells. In most instances several terminal axons are grouped and enclosed by a Schwann cell, single axons being rare. All terminal axons are able to take up and to store 5-hydroxydopamine which strongly suggests that they are adrenergic. The innervation of the renal vein is more sparse than that of the muscular arteries but somewhat denser than that of the elastic artery. In addition, close to the origin of the renal artery the presence of “small intensively fluorescent” (SIF) cells as well as of some adrenergic ganglion cells is noted. The latter are situated in the adrenergic nonterminal axon bundles, which run parallel to the blood vessels. It is concluded that the uneven adrenergic innervation along the artery as well as individual variations in the branching of the artery are the main causes of the unusually high individual variations of the NA content of this organ such as used in pharmacological experiments.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 138 (1973), S. 295-298 
    ISSN: 1432-0878
    Keywords: Cornea epithelium ; Precorneal film ; Domestic fowl ; Ruthenium red ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das vordere Corneaepithel des Haushuhnes besteht aus 5 Schichten. Die oberflächlichste Lage hat einen Zottenbesatz. Die 0,2 μ langen Mikrovilli haben eine Dicke von 0,04–0,05 μ und einen Abstand von höchstens 0,1 μ voneinander. Auf der freien Oberfläche liegt ein mit Rutheniumrot anfärbbarer Film von Glykosaminoglykanen von 0,26–0,3 μ Dicke. Die Mikrovilli ragen in diesen Film hinein. Dieser Film ist für den spiegelnden Glanz der Cornea verantwortlich. Die Tränensekretion kann sehr gering sein, weil ein Teil der Flüssigkeit an die sauren Mukopolysaccharide gebunden ist. Die Moleküle dieses Films werden wahrscheinlich in der oberen Zellage synthetisiert.
    Notes: Summary The anterior cornea epithelium of the house-hen consists of 5 layers. The outermost layer has a villus border. The 0.2 μ long microvilli are 0.04–0.05 μ thick and are not more than 0.1 μ apart. A film of ruthenium red stainable glycosamine Glycans of 0.26–0.3 μ thickness lies on the free surface. The microvilli protrude into this film. This film is responsible for the reflecting shine of the cornea. The tear secretion can be kept at a low level as a part of the fluid is bound to the acid mucopolysaccharides. The molecules for this film are probably synthesized in the outermost cell layer.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 138 (1973), S. 345-370 
    ISSN: 1432-0878
    Keywords: Axonal migration ; Catecholamines ; Sciatic nerve ; Radioautography ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The radioautographic technique has been used to study the axonal migration of catecholamines in sympathetic fibres of the sciatic nerve of rats after ligature. A first series of experiments aimed at ascertaining the capacity of the proximal portion of adrenergic fibres to take up and store exogenous tritiated catecholamines (3H-DOPA; 3H-DA and 3H-NA) 3 to 22 hours after ligation. The results are qualitatively similar in rats pretreated and non-pretreated with IMAO, but the intensity of the radioautographic reaction is lower in the latter cases. Most of the labeled axons are filled mainly with vesicular and tubular profiles of endoplasmic reticular origin, large dense bodies (probably lysosomes) and/or mitochondria. The silver grains are generally superimposed on the vesicular and/or the tubular profiles, but in some cases on the large dense bodies, suggesting that exogenous catecholamines can be stored in lysosomes. The question whether SGV specifically store catecholamines also in the modified adrenergic fibres has been investigated in KMnO4 fixed material. These results show that beside a large number of fibres in which there is a strict correlation between labeling and SGV, some fibres containing SGV do not retain the 3H-NA. Conversely some fibres which contain mainly agranular vesicles display radioautographic reaction. Therefore, in case of ligated fibres, SGV cannot be considered the specific organelles for storage of catecholamines. The axonal migration of labeled catecholamines has been studied in animals pretreated with IMAO. A moderate, but selective, labeling is present in the proximal portion of sciatic fibres of rats in which administration of labeled catecholamine preceeded of 2 hours the ligature and this was performed 22 hours before fixation. From these combined types of experiments, it is concluded that despite the presence of all the structures necessary for the storage of a high amount of catecholamines in the modified adrenergic fibres, only a small fraction of catecholamines accumulated above the ligature has been transported by axonal migration. Therefore, the axonal migration of catecholamines appears as an epiphenomenon related to the distal migration of enzymatic and storage proteins from the perikaryon.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 136 (1973), S. 447-460 
    ISSN: 1432-0878
    Keywords: Spermatids (rat) ; Manchette ; Microtubules ; Influence of Colcemid ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Links unusual for their length and variable morphology have been described between manchette microtubules in late stages of rat spermiogenesis. In earlier stages of rat spermiogenesis obvious links longer than ∼160 Å are rare, the majority being ∼80 or ∼120 Å in length. The most easily discernible geometric pattern in cross-sections of assemblies of manchette microtubules in intermediate stages of rat spermiogenesis is that of linear arrays sometimes resulting in long and irregularly folded chains of closely linked microtubules. Colcemid disrupts these arrays and is responsible for the formation of more complex geometric patterns. Six hours after drug administration the manchette is dramatically reduced in length. Sheet-like links of variable dimensions and 〉160 Å in length interconnect not only microtubules but C-type microtubules as well as other links. These links are similar in morphology to those found in later stages of rat spermiogenesis. It is suggested that the formation of these links may perhaps be dependent upon aspects of microtubule disassembly.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 139 (1973), S. 463-471 
    ISSN: 1432-0878
    Keywords: Gallbladder (Human) ; Mucus secretion ; Reverse pinocytosis ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Mucous secretory activity of the human gallbladder epithelium was investigated by light and electron microscopy and with histochemical techniques. There are two types of granules in the supranuclear region of the epithelial cells. The one low in density contains a fine filamentous material and gives a strongly positive silver methenamine reaction. The other is dense and only faintly positive. The granules of the former are considered to be mucous secretory granules and the granules of the latter may be lysosomes. PAS positive granules correspond presumably to both types of granules mentioned above. The mucous secretory granules are considered to be synthesized by the Golgi apparatus and the granular endoplasmic reticulum as has been confirmed in other mucous secretory cells. Their content is released from the cell by reverse pinocytosis. Typical goblet cells occur frequently in the fetal epithelium, but cannot be observed in the adult specimens.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 137 (1973), S. 421-434 
    ISSN: 1432-0878
    Keywords: Giant mitochondria ; Transitional epithelium ; Urinary bladder (mole) ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Harnblasenepithel des Maulwurfs wurde elektronenmikroskopisch untersucht. Bei bestimmten Tieren finden sich in den Intermediärzellen „matrixreiche“ Riesenmitochondrien. Diese Riesenmitochondrien scheinen aus normalen Mitochondrien hervorzugehen und enthalten verschieden geformte Einschlüsse. Andere Organe und Zellen bei Maulwürfen mit Riesenmitochondrien in den Intermediärzellen des Harnblasenepithels weisen normale Mitochondrien auf. Es handelt sich demnach hier um eine sog. „Mitochondriose der Intermediärzellen“. Bedeutung, Bildung und Abbau der Riesenmitochondrien werden diskutiert.
    Notes: Summary Giant mitochondria containing an enormous matrix volume were found in the intermediary cells of the urinary bladder transitional epithelium of the mole. Regularly shaped mitochondria develop club-like protrusions forming giant mitochondria that contain several types of inclusions. Various other tissues were examined, but we could state that giant mitochondria exist only in the intermediary cells of the urinary bladder epithelium. Thus a peculiar “intermediary cell mitochondriosis” is described in this paper, not regularly occurring in the mole. The functional significance of the giant mitochondria is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    ISSN: 1432-0878
    Keywords: Annulate lamellae ; Annelidae ; Oogenesis ; Endocrinology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'évolution en l'absence d'hormone cérébrale provoque, dans les ovocytes de N. diversicolor, la formation de lamelles annelées cytoplasmiques (L.A.). Le processus débute par l'apparition de lames de réticulum à proximité du noyau (15 jours d'évolution à 15° C). Les lames se rapprochent ensuite du noyau et des pores apparaissent, situés le plus souvent face à ceux de l'enveloppe nucléaire (20ème jour). La différenciation des lames du réticulum en L.A. progresse ensuite depuis les éléments les plus proches du noyau vers les plus externes. Dans le cytoplasme des ovocytes ayant évolué à la température de 20° C, on assiste en outre à la formation d'empilements de citernes ergastoplasmiques. Ces citernes, non situées à proximité du noyau, subissent également une transformation progressive en L.A. L'étude cytochimique effectuée par digestion enzymatique a montré que la pepsine dégrade fortement le matériel dense des lamelles annelées. Ce matériel semble donc renfermer une teneur élevée en protéines auxquelles pourrait se trouver associé du RNA.
    Notes: Summary Experimental elimination of brain activity leads to the formation of cytoplasmic annulate lamellae (L.A.) in oocytes of N. diversicolor. This process begins with the appearance of cisternae of endoplasmic reticulum in the vicinity of the nucleus (15 days of development at 15° C). Then, the cisternae move closer to the nucleus and pores appear, often facing the pores of the nuclear envelope (20th day). The differentiation of endoplasmic reticulum into L.A. progresses from the elements closest to the nucleus to the more peripheral ones. In the cytoplasm of oocytes which developed at 20° C, stacks of cisternae of rough endoplasmic reticulum have been observed. These cisternae, which are not localized near the nucleus, also undergo a progressive transformation into annulate lamellae. A cytochemical study, based on enzymatic digestion, shows that pepsin strongly digests the dense material of L.A. This material, therefore, seems to contain a high amount of proteins, perhaps associated with RNA.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 137 (1973), S. 553-561 
    ISSN: 1432-0878
    Keywords: Lung (frog) ; Alveolar epithelium ; Cytosomes ; Alveolar lining layer surfactant ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Alveolarepithel der Froschlunge weist nur einen einzigen Zelltyp auf. Die Zellkörper sitzen in den Nischen zwischen den Kapillaren, die sie mit Zytoplasmaausläufern überdecken. Die Epithelzellen enthalten große Zytosomen mit osmiophilen Lamellen mit einer Periode von 40–42 Å. Sie sind den Typ II-Pneumozyten der Säugerlunge vergleichbar. Das Alveolarepithel der Froschlunge ist mit einer Grenzschicht bedeckt, die in Abhängigkeit von der Fixierung eine 40–42 Å-Periode aufweist oder aus einer oder mehreren Doppelmembranen zusammengesetzt ist. Gittermuster und Myelinfiguren sind vorhanden. Das bedeutet, daß Surfactant in der Froschlunge in gleicher Weise wie in der Säugerlunge dargestellt werden kann.
    Notes: Summary The alveolar epithelium of the frog exhibits only one type of cells. The cell-bodies are situated in the spaces among the capillaries, which they cover with cytoplasmic extensions. The epithelial cells contain large bodies (cytosomes) with osmiophilic lamellae having a period of 40–42 Å. The alveolar cells are considered to be similar to the type II-pneumocytes of mammalian lungs. The alveolar epithelium of the lung of the frog is covered with a lining layer, which depending on the method of fixation consists of periods of 40–42 Å or of one or more double membranes. Lattice formations and myelin figures are seen. This means that the surfactant in the lung of the frog can be demonstrated in the same way as in mammalian lungs.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 140 (1973), S. 481-496 
    ISSN: 1432-0878
    Keywords: Synaptosomes ; Dense projections ; Complex vesicles ; Serial sections ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Synaptosomes and synaptic junctions have been examined employing serial sections, with emphasis placed on four areas of investigation. 1. Starting from unequivocal synaptosomal profiles and tracing them through consecutive sections to the periphery of the synaptosomes, it is clear that vesicles are the one constant feature of the presynaptic terminal. In no instance was it possible to identify an empty membranous profile as synaptosomal. 2. Following a similar procedure it was found that the criteria required to predict the existence of a junctional region within a synaptosomal profile are: the accumulation of synaptic vesicles at one locus within its presynaptic component, and the presence of a postsynaptic profile characterized by two or more junctional features. 3. Serial sections of non-osmicated, PTA stained synaptic junctions confirm the regularity and orderliness of dense projection distribution along the length of the junction. 4. Complex vesicles can usually be followed in two and sometimes three adjacent sections, appearing either as intact vesicles or empty shells. Further observations confirmed that the latter profiles may be sections through the periphery of intact vesicles or through isolated shell fragments. They are more common in the latter form in unbuffered material.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 141 (1973), S. 255-283 
    ISSN: 1432-0878
    Keywords: Glandula harderiana ; Anatidae ; Electron microscopy ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Hardersche Drüse von Anser anser, Anas platyrhynchos und Cygnus olor wurde cytochemisch, licht- und elektronenmikroskopisch untersucht. Vergleichend-anatomisch ergibt sich für die drei Species derselbe Drüsenaufbau. Sie bestehen aus Läppchen bzw. kurzen Tubuli, die von einem einschichtigen, hochprismatischen Epithel ausgekleidet sind, das sich auf die in die Tubuli hineinragenden Leisten bzw. Zotten fortsetzt. Es müssen zentrale und periphere Drüsenabschnitte unterschieden werden. Nur die zentralen Zellen enthalten neutrale und saure Mukosubstanzen. In Semidünnschnitten (Richardson) erweisen sich die peripheren Drüsenzellen als stark vakuolisiert. Zentralwärts nimmt die Vakuolisierung ab, die basale Basophilie nimmt zu. In den Harderschen Drüsen von Gänsen und Enten wurden neben Hydrolasen eine Reihe von Oxydo-Reduktasen aus der Glykolysekette, dem Citratzyklus und der Atmungskette sowie die Enzyme G-6-PDH, GDH, β-HBDH und GLuDH nachgewiesen. Die zentralen Drüsenabschnitte sind mit hohen Aktivitäten der glykolytischen Oxydo-Reduktasen und der NADPH2-liefernden Enzyme ausgestattet. Hydrolytische lysosomale Enzyme, Esterasen und Phosphatasen sind in der Harderschen Drüse nur in geringer Menge vorhanden. Stets können cholinerge Nerven nachgewiesen werden. — Elektronenmikroskopie: Alle Drüsenzellen werden an den apikalen seitlichen Kontaktflächen durch ein differenziertes Schlußleistennetz (Zonulae occludentes, Zonulae adhaerentes, Desmosomen) verbunden. An den zentralen Drüsenzellen lassen sich eine Basalzone (Zellkern, ER), eine ausgedehnte Golgi-Zone und ein apikales Zell-areal unterscheiden. Die Sekretvakuolen entstehen durch Membranabknospung aus dem Golgi-Apparat, ihr Sekret wird durch Ruptur des apikalen Plasmalemms extrudiert. Die peripheren Drüsenzellen weisen strukturelle Merkmale von Becherzellen auf. Ein schmaler basaler Cytoplasmabezirk enthält den komprimierten Kern, der übrige Zellraum überwiegend leere Vakuolen, Membranreste, Lamellenkörper und Lysosomen. Terminale Nervenfasern mit bekannter Innenstruktur durchbrechen die Basalmembran und lagern sich den Drüsenzellen eng an, teilweise in Vertiefungen ihrer basalen und basolateralen Oberfläche eingebettet. Diese terminalen Axone enthalten massenhaft synaptische Vesikel, vereinzelt Bläschen mit einem massendichten Granulum und Mitochondrien. Spezialisierte prae- und postsynaptische Membranen kommen nicht vor.
    Notes: Summary The Harderian gland of Anser anser, Anas platyrhynchos and Cygnus olor has been investigated cytochemically, light microscopically and ultrastructurally. Comparison of these glands within the three species reveals identical structures. The surface of the short glandular tubules carries a single-layered, cylindrical epithelium, which continuously covers all the villi protruding into the tubular lumen. There is evidence for a significant difference between the central and peripheral parts of the glandular tubules. Cytochemical reactions for neutral and acid mucosubstances are positive only in central glandular parts. The semi-thin sections (Richardson staining) show highly vacuolated glandular cells within the peripheral areas. This vacuolisation decreases the more centrally the cells are situated, but conversely their basal basophilic staining increases towards the center. Within the Harderian gland of geese and ducks we have localized by histochemical means several hydrolases and oxydoreductases which reflect enzyme activities of the glycolytic pathway, the citrate cycle, and related metabolic pathways. The activities of glycolytic oxydoreductases and the pentose phosphate pathway enzymes are remarkably high within the central glandular parts. Lysosomal hydrolases, esterases and phosphatases are only to be demonstrated in very moderate degree of activity. All specimens of the Harderian gland contain cholinergic nerves. The ultrastructural analysis reveals highly differentiated apical cellular contacts (zonulae adhaerentes, desmosomes). There are only small intercellular spaces. The centrally located glandular cells can be divided into three compartments, a basal zone containing the nucleus and endoplasmic reticulum, a large Golgi zone and an apical zone containing abundant secretory vacuoles, which emerge from the Golgi apparatus. The secretory products are extruded by rupture of the apical cellular membrane. — The peripheral glandular cells show many similarities to goblet cells. There is only a small basal cytoplasmic are which contains a compressed nucleus, whereas the whole cell is filled with mostly empty vacuoles, membranes, lamellar bodies and lysosomes. — Terminal nerve fibres penetrate the basal lamina and make contact with the glandular cells. The terminal axons contain abundantly synaptic vesicles, sporadic dense cored vesicles and mitochondria. Until now, we could not find any specialized presynaptic or postsynaptic membranes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 141 (1973), S. 401-412 
    ISSN: 1432-0878
    Keywords: Pulmonary epithelium ; Human fetus ; Endocrine cells ; APUD cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopic investigations of the pulmonary epithelium of human foetuses reveal the occurrence of cells exhibiting fine-structural characteristics of polypeptide hormone producing APUD cells. Three types of cells were identified mainly on basis of the morphology of their secretory granules. Cells of type 1 have the appearance of monoamine storing cells and the dense core of vesiculated granules of these cells are reactive to argentaffine reaction performed directly on ultra-thin sections. Cells of type 2 contain granules of uniform shape and size and of rather homogeneous appearance. Besides in larger bronchial tubules these cells are localized in the epithelium of developing alveoli. Cells of type 3 with large osmiophilic granules tightly bound by a membrane are few and scattered. These cells are observed in larger bronchial tubuli only.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 141 (1973), S. 413-425 
    ISSN: 1432-0878
    Keywords: Seminiferous tubules, human ; Lamina propria ; Contractile cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the lamina propria of human seminiferous tubules was analyzed in normal specimens and compared to biopsies showing great thickenning of this area in light microscopy. The contractile cells are stellate in shape, the intercellular gaps between their branchings being less than 150 Å. The cytoplasmic features of these cells are similar to those described by Ross and Long (1966) and do not differ significantly in the pathological cases examined. The intercellular components, namely collagen fibers, microfibrils and an incomplete basement membrane-like coating of the contractile cells, are strikingly increased in the thickenned lamina propria, although the number of layers making up this structure needs not be increased. Occasionally, the intercellular space is occupied by only one of these materials. The distribution of collagen permits identification of two main patterns in the thickenned lamina propria: a) one where the basement membrane of the seminiferous epithelium is separated from the first layer of contractile cells by a wide collagen zone, and b) another case where the layer displaying greater thickness because of increased collagen deposition is located further away from the germinal epithelium. The functional activity of the contractile cells, the physiological implication of structural alterations of the lamina propria and the necessity to correlate these observations to andrological findings, are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 141 (1973), S. 459-468 
    ISSN: 1432-0878
    Keywords: Cell adhesion ; Morphogenesis ; Chick Embryo ; Cell membrane ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The unincubated chick blastoderm, which consists of a complete upper epithelial layer of one cell thickness (epiblast) and an incomplete lower layer (hypoblast), was examined with the electron microscope in order to define the types of cell contact present. The terminal contacts between the cells of the epiblast invariably involved several focal tight junctions, but only occasionally involved tight junctions. Desmosomes were not observed in these areas, but were encountered in various phases of development in the deeper contact regions between epiblast cells. This deeper region also showed sporadic focal tight junctions and frequent micropapillae. These micropapillae were also common on the surfaces of hypoblast cells. Intercellular spaces between epiblast and hypoblast cells and within the hypoblast were often wide, narrowing to occasional focal tight junctions. Tight junctions and desmosomes were not observed in association with hypoblast cells. Gap junctions were not observed in any region of the embryo. These observations are discussed in relation to the morphogenetic movements occurring in the forming hypoblast and also the influence of this layer on the subsequent development of the embryo. Comparisons are drawn between the contact morphology in the unincubated blastoderm and that in later stages of development.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 141 (1973), S. 479-492 
    ISSN: 1432-0878
    Keywords: Malpighian tubule ; Carausius morosus ; Water balance ; Diuretic hormone ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Carausius morosus starved and deprived of water lose about 30% of their body weight in 4 days, mainly due to water loss. Isolated inferior tubules from starved dehydrated insects secrete urine at 0.041 nl·mm−1·min−1 compared with 0.118 nl·mm−1·min−1 in those from fed hydrated insects. This difference is due partly to the level of a diuretic (and perhaps also an antidiuretic) hormone in the haemolymph acting directly on the urine-secreting mechanism and partly to changes in the intrinsic capacity of the tubule cells for urine secretion. This latter change is accompanied by structural changes in the tubules. During starvation and dehydration the lumen becomes packed with white granules, the height of the type 1 cells is reduced, their basal infoldings and brush border become shorter and their mitochondrial volume is reduced.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 141 (1973), S. 529-544 
    ISSN: 1432-0878
    Keywords: Osteoclast ; Parathyroid hormone ; Lysosomes ; Bone resorption ; Electron microscopy ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Young rats were treated with high doses of parathyroid hormone (PTH). Osteoclasts from these animals revealed characteristic alterations in comparison to control cells: a) The cytoplasm contained large vacuoles with phagocytosed cells, some of which resembled osteoblasts or osteocytes. The vacuoles were interpreted as lysosomes because the engulfed cells often appeared partly digested and the vacuoles contained acid phosphatase as demonstrated histochemically, b) lipid droplets were present in the cytoplasm and usually located close to the endoplasmic reticulum and/or in regions with many free ribosomes, c) the Golgi complex was more frequently separated from the nuclei than in control cells, d) small coated cytoplasmic bodies were numerous in the peripheral cytoplasm, e) the membranes of the endoplasmic reticulum were fused in some places, f) cytoplasmic regions with numerous free ribosomes were frequent, g) large ring-shaped granules occurred in some mitochondria. Energy dispersive X-ray analysis of these granules provided evidence that they contained calcium and probably phosphorus, h) in some osteoclasts the mitochondria were enlarged. — The findings are consistent with an increased activity of osteoclasts and in particular a stimulation of the lysosomal system in these cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    ISSN: 1432-0878
    Keywords: Paracrystals ; Reinke crystals ; Leydig cells ; Normal human testis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary One of two types of paracrystalline inclusions, other than Reinke crystals, was encountered in the Leydig cells of the normal mature testes of 9 out of 10 patients. The basic ultrastructure of these formations was that of parallel arrays of fine filaments (8 cases) or tubules (1 case). The filamentous structures, designated as type A paracrystals, consisted of fascicles of parallel rows of 4 or 5 dense fibrils. The latter typically contained dense granules or banded striations spaced at regular intervals. In 4 cases the inclusions were found in the cytoplasm while in 4 others they were confined to the nuclei. The tubular type of paracrystal, type B, was observed in only one patient. Here, groups of closely packed tubular inclusions occupied large portions of cytoplasm. The tubular walls were composed of closely applied, small, circular profiles. In no instance were paracrystals and Reinke crystals encountered in the same cell. A possible role of the former as precursors of the latter is discussed but there is no strong supporting evidence for this despite certain suggestive similarities in unit and subunit measurements.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    ISSN: 1432-0878
    Keywords: Median eminence (Rabbit) ; Dense-core vesicles depletion ; Releasing factors ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of mating on the depletion of osmiophilic material from dense-core vesicles (DCV) within the external layer of the rabbit median eminence (ME) were investigated. Two different populations of DCV were demonstrated within the ME external layer of the non-mated control animals. A plot of the diameters of these vesicles showed two peaks, one at 90–100 nm, and the other at 120–130 nm. These two populations of DCV were found in separate axons and axon terminals in contact with, or near the perivascular spaces of, portal capillaries. Within these axons and terminals an occasional membrane profile or “vesicle ghost” was also observed. The same two populations of DCV were evident in the ME external layer of animals that were sacrificed at 10 minutes post-coitus. In these experimental animals, the number and size of the smaller population of DCV were the same as those of the none-mated controls. However, there was an obvious decrease in the number of the large (120–130nm) DCV, together with a simultaneous marked increase in the number of “vesicle ghosts”. These ghosts had a mean diameter of 137±14 nm. On the basis of their size, it is suggested that the “vesicle ghosts” represent large DCV that have been depleted of their content following mating. Ultrastructural evidence for the depletion of osmiophilic material from the large DCV of mated animals is provided. According to previous writers the smaller DCV within the ME are aminergic, whereas the larger DCV may contain releasing factors (RF). Our findings provide further morphological evidence to support this hypothesis. Furthermore, RF and biogenic amines appear to be contained within separate nerve terminals in the rabbit ME.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 142 (1973), S. 63-68 
    ISSN: 1432-0878
    Keywords: Snail ; Regeneration of eye ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distal half of the posterior tentacle of adult Helix aspersa and Cryptomphallus aspersa was removed and the proximal half was studied with light and electron microscopy after different intervals. The tentacle itself does not regenerate, but the receptor organs at the distal end of the normal tentacle differentiate at the level of the section. The newly formed eye is smaller than the control; however, its components and subcellular characteristics resemble those of the normal eye.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 277 (1994), S. 557-564 
    ISSN: 1432-0878
    Keywords: Key words: Slice culture ; Cerebral cortex ; Astrocytes ; Orthogonal arrays of particles - Freeze-fracture ; Electron microscopy ; Rat (Lewis)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The ultrastructure of astrocytes in an organotypic slice culture of the rat visual cortex was investigated using ultrathin sections and freeze-fracture replicas. After a culture period of 9–15 days, a glial scaffold formed that separated the bulk of the slice neuropil from the medium and the underlying plasma clot. However, the glial cells and processes did not build a dense barrier but allowed the outgrowth of neurites. A basal lamina covering the medium-oriented surface of the astrocytes was not found. In freeze-fracture replicas, orthogonal arrays of particles (OAP) were characteristic components of astrocytic membranes. The OAP density in membranes bordering the medium was 35±13 OAP/μm2, corresponding to 2.5% of this membrane area; the OAP density in membranes within the slice neuropil was 22±12 OAP/μm2, corresponding to 1.4% of this membrane area. Although the difference was significant, it was greatly reduced when comparing OAP densities in endfoot and non-endfoot membranes in vivo. Another mode of polarity was recognized in astrocytes of the organotypic slice culture. In membranes of astrocytes bordering upon the medium, the density of non-OAP intramembranous particles (IMP) was clearly higher (1130±136 IMP/μm2) than in membranes of astrocytes in the center of the slice (700±172 IMP/μm2). This pronounced IMP-related polarity was observed neither in vivo nor in cultured astrocytes. The present study suggests, together with data from the literature, that the distribution of astrocytic OAP across the cell surface is influenced by the existence of a basal lamina and neuronal activity, and that astrocytes possess a more remarkable plasticity of membrane structure than previously suspected.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    ISSN: 1432-0878
    Keywords: Integument ; Hirudinea ; Sensory organs ; Nerves ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Le tégument de Glossiphonia complanata comprend, outre les cellules épithéliales banales, de nombreux organes particuliers ou organes de Bayer, regroupés essentiellement sur la face dorsale de l'animal. Ils sont formés par une cellule apicale saillante enchassée dans une cellule musculaire en anneau. L'ensemble de ces formations est étudié du point de vue ultrastructural. Des cellules épithéliales partent des fibres nerveuses afférentes, sans doute vecteur des perceptions de stimuli mécaniques de pression au niveau du tégument; la réponse se faisant sans doute par la contraction de la cellule basale de chaque organe de Bayer, innervée par des fibres nerveuses efférentes, entrainant la saillie de la cellule apicale. Le hérissement de ces nombreuses papilles du tégument dorsal pourrait être un signal perçu par le partenaire sexuel, chez cette Hirudinée à fécondation hypodermique.
    Notes: Summary The integument of Glossiphonia complanata, built up by epithelial cells, contains numerous particular organs (Bayer organs), mainly on the dorsal side of the animal. They consist of a protuberant apical cell, which is surrounded by a ring-shaped muscle cell. All the integumentary formations are studied from an ultrastructural point of view. From the epithelial cells issue afferent nerve fibres, considered as vectors of the perception of mechanical stimuli of pressure at the level of the integument; the response no doubt operating by the contraction of the basal muscle cell of each Bayer organ, innervated by efferent nerve fibres, bringing forth the protrusion of the apical cell. The erection of these numerous papillae of the dorsal integument might be a signal perceived by the sexual partner, fecundation occurring in this group of leeches under the integument.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 143 (1973), S. 505-515 
    ISSN: 1432-0878
    Keywords: Endoplasmic reticulum ; Paracervical ganglion (Rat) ; Neurosecretion ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two new types of structure of the cytoplasm of an autonomic neuron were described: (1) Inclusions of the rough ergastoplasmic reticulum, which were named “ergastosomes”, contain finely granular material with moderately electron opaque staining with both glutaraldehyde-OsO4 and KMnO4 fixations. A short comment was made on the nature of the contents of the ergastosomes. (2) Tubular formations of endoplasmic reticulum were found in the axons and/or dendrites of the paracervical ganglion.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    ISSN: 1432-0878
    Keywords: Nervous system ; Stick insect ; Blood-brain barrier ; Development ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fat body sheath which surrounds the ventral nerve cord of the adult stick insect, Carausius morosus, is absent in the hatchling. Since the haemolymph sodium ion compositions of the two stages are similar, it is suggested that the fat body sheath is not a site of a blood-brain barrier dealing with extra-axonal regulation of sodium. Similarities of ultrastructure in connectives of adults and hatchlings are demonstrated, and tight junctions are shown to occur in perineural cells of both stages. The possible significance of this to the blood-brain barrier of this insect is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 145 (1973), S. 363-388 
    ISSN: 1432-0878
    Keywords: Heart ; Monkey ; A-V node and bundle ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The atrio-ventricular (A-V) node of the monkey heart is located in the focus of converging atrial muscle. Three main atrial muscle strands, coming from the atrio-ventricular ring, the dorsal wall of the atria, and the ventral part of the atrial septum, converge in the nodal region where they overlap and are interconnected. The junctional type of fibers establishing interconnection between the atrial muscle and the nodal tissue are not strictly localized at the periphery of the node, but may be traced further, along the A-V ring and coronary sinus. The A-V node consists of a loose peripheral and a compact distal part. In the former, typical nodal fibers were found, while the compact part shows an important individual variation in structure and cell-types. In some monkey hearts, the nodal fibers gradually become broader bundle fibers, while in other specimens the junctional fibers surround the compact part and than penetrate the nodal-His (N-H) region. These junctional fibers become nodal fibers or are in terminal contact with large clear cells up to 50 μ in diameter. Clear cells of various diameters are often intercalated between the cell rows of the nodal and His-bundle fibers and may form a distinct cellular gate between the node and the His-bundle.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...