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  • Springer  (117)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 10 (1972), S. 82-90 
    ISSN: 1432-0827
    Schlagwort(e): Calcium ; Phosphate ; Precipitation ; Kinetics ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: 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.
    Kurzfassung: 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.
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 16 (1974), S. 145-152 
    ISSN: 1432-0827
    Schlagwort(e): EHDP ; Bone ; Chemistry ; Serum ; Rabbits
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 23 (1977), S. 13-17 
    ISSN: 1432-0827
    Schlagwort(e): Dental calculus ; Glycopeptide ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary A method is described for the isolation and purification of a sulphated glycopeptide from human supragingival calculus. The compound was isolated after using EDTA treatment, 2 M CaCl2 extraction, proteolytic digestion, ethanol precipitation, and finally purified by DEAE cellulose chromatography. It migrated as a single component on cellulose acetate electrophoresis, and chemical and infrared spectral analysis showed the presence of covalently attached sulphate groups. The sulphated glycopeptide was distinguished from being a sulphated glycosaminoglycan.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 1432-0975
    Schlagwort(e): Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract  We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 15 (1980), S. 79-101 
    ISSN: 1432-1432
    Schlagwort(e): Molecules ; Interstellar ; Chemistry ; Isotopes ; Solar system
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The study of interstellar molecules broadly includes two areas of interest. One area uses the unique ability of molecules to act as probes of the physical conditions in the cold, dense, visually opaque component of the interstellar medium. The physical properties of this and other components of the interstellar medium are summarized. The other area deals with the chemistry of interstellar molecules, recent aspects of which are emphasized in this review. Gas-phase chemistry, shock chemistry, and grain surface chemistry are discussed in the context of recent observations. No present observations suggest that surface reactions are relevant, but neither can they be ruled out. Ion-molecule reactions are clearly operative, at least for the simpler species. Chemical isotope fractionation is reviewed, andd it is concluded that the complexities of the chemistry allow no cosmological conclusions to be drawn from observations of deuterium in interstellar molecules, while the presence of13C in interstellar molecules permits an estimate of the12C/13C ratio which is consistent with the current concepts of the nucleosynthesis history of the Galaxy. Possible connections between interstellar molecules and the early molecular history of the solar system are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 173 (1993), S. 77-84 
    ISSN: 1432-1351
    Schlagwort(e): Crayfish ; Abdominal posture system ; Cross connections among motoneurons ; Double marking of cells ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Intracellular recordings and dye injections were used to examine mutual coupling among slow abdominal postural motoneurons in the 4th abdominal ganglion in crayfish (Procambarus clarkii). Intracellular current injection into one motoneuron altered the spike firing rate of some of its synergists. Depending on the polarity of the injected current, the premotor effect on the synergists was excitatory or inhibitory. The magnitude of the effect was intensity dependent. No dye coupling was found among the motoneurons following injection of Lucifer yellow. The morphological basis of the coupling was examined by differential filling of motoneuron pairs, one with horseradish peroxidase and the other with Lucifer yellow. The stained motoneurons were simultaneously visualized under light microscopy to determine the proximity of their differently colored dendrites. It was thus possible to locate the site of the presumed monosynaptic contacts between them. Combined physiological and morphological evidence suggests that these neurons are mutually coupled, forming part of an integrative system for abdominal posture control in crayfish.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    The international journal of advanced manufacturing technology 14 (1998), S. 894-900 
    ISSN: 1433-3015
    Schlagwort(e): Aerodynamics ; Concurrent engineering ; Manufacturing costs ; Optimisation ; Statistical models ; Tolerances
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract A component of the direct operating cost of aircraft is that associated with the manufacturing cost. This affects depreciation, interest, insurance and maintenance charges. By relaxing the requirements for aerodynamic surface smoothness the manufacturing cost can be reduced at the expense of an increase in drag and corresponding fuel costs. This work is part of a study to examine this multidisciplinary problem. Only isolated turbofan nacelles are considered. The costs associated with assigning different tolerance levels to the feature dimensions on nacelles are assessed. A statistical procedure is employed to estimate the cost-tolerance relationship for eleven features involving gaps, steps, surface profile and fastener flushness. This procedure requires actual manufacturing and cost source data. A knowledge of the cost-tolerance relationships is useful in a concurrent engineering context. It will allow aerodynamicists to optimise surface smoothness in consultation with production engineers, thus achieving the best compromise between cost and drag.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 34 (1999), S. 199-229 
    ISSN: 1572-9648
    Schlagwort(e): Aerodynamics ; Kutta condition ; Edge singularities ; Boundary integral equations ; Fluid dynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract This review paper presents a unified formulation of the Kutta condition for steady and unsteady flows, implemented by removing all unbounded velocity singularities (of power‐law and logarithmic type) at the trailing edge, and including nonlinear wakes and thick swept‐back wings. A suitable boundary integral approach is adopted and the uniqueness issue is discussed for several wing configurations of interest in aerodynamics. Sommario. Si presenta una formulazione unificata della condizione di Kutta per flussi stazionari e non stazionari, ottenuta imponendo la limitatezza della velocità al bordo d'uscita, e valida nel caso nonlineare anche per ali a freccia. Si utilizza un opportuno approccio integrale al contorno e si discute il problema dell'unicità per svariate configurazioni alari di interesse nelle applicazioni.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    ISSN: 0931-1890
    Schlagwort(e): Key words Air pollution ; Light microscopy ; Pinus sylvestris ; Nutrients
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract  The mesophyll structure of current and second year needles of mature Scots pines (Pinus sylvestris L.), growing on a survey line from the Karelian Isthmus (N.W. Leningrad region, Russia) to S.E. Finland, was studied at the light microscopic level in 1992 and 1994. The area is affected by sulphur dioxide and nitrogen oxide emissions from Russia (200  000–285 000 ton/year SO2 and about 100  000 ton/year NOX), Estonia (140  000–320  000 ton/year SO2 and 30  000–50  000 ton/year NOX) and Finland (6000–9000 ton/year SO2 and 23 000–25 000 ton/year NOX) and by unknown amounts of neutralizing compounds from Estonia. Mean concentrations of SO2 were between 1.0 and 1.5 μg m–3 and those of ozone between 52 and 61 μg m–3 during growing seasons of 1991–1994. The concentrations tended to be lower in 1993/94 than in 1991/92. The results showed cellular changes related to exposure to sulphur dioxide, ozone and acid wet deposition. The percentage of cells with injuries related to acid deposition was higher in 1994 than in 1992, possibly due to higher reduction of neutralizing than of acidifying compounds in the main emission areas, while the percentage of cells with injuries related to sulphur dioxide correlated positively with needle sulphur concentrations and showed a declining trend between Karelian Isthmus and S.E. Finland in the needles sampled in 1992. These changes and those related to ozone were considerably less numerous in 1994 than in 1992, possibly on account of the lower concentrations of SO2 and ozone in 1993/94 than in 1991/92, especially in early summer, the time of the most sensitive phase of needle growth. In addition, periods of lower wet deposition in summer 1992, and considerably lower temperatures in autumn/winter 1992 than in 1994 may have enhanced the injuries in the needles collected in October/December 1992, relative to those collected in 1994. The results of the microscopic work agreed well with the simultaneous chemical measurements, pointing to the usefulness of cellular analysis for diagnostic work in the field.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Pure and applied geophysics 118 (1980), S. 128-151 
    ISSN: 1420-9136
    Schlagwort(e): Galactic cosmic rays ; Solar proton events ; Particle precipitation ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O3 is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O3 is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O3. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°≲Λ≲70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O3 depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Aquatic sciences 51 (1989), S. 108-128 
    ISSN: 1420-9055
    Schlagwort(e): Chemistry ; mountain lakes ; silica ; acidity ; sediment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Alpine lakes in siliceous catchments of Tyrol and Carinthia (Austria) show signs of acidification. About 9% of the studied lakes have no alkalinity, more than 20% are below pH 6. About two thirds of all lakes have acid neutralizing capacities below 100 μeq 1−1. In spite of moderate precipitation acidity, some lakes show considerable concentrations of dissolved reactive aluminum during or shortly after snowmelt. High altitude lakes of the Alps are definitely more acidic than high mountain lakes in remote areas. Large differences in water and soil chemistry of nearby situated lakes were attributed to heterogeneities of bedrock geology. Paleolimnological investigations on former pH values of five lakes, based on diatom assemblages in the sediment, showed different developments: recent and past acidification, stable conditions, and alkalinization.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Accreditation and quality assurance 5 (2000), S. 409-413 
    ISSN: 1432-0517
    Schlagwort(e): Key words Metrology ; Comparisons ; Chemistry ; Standards
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract  After stressing the importance in the modern world of accurate and reproducible measurements, the actions taken by the Bureau International des Poids et Mesures to set up, together with the regional metrology organizations, a series of key comparisons are described. They are the technical foundation of a mutual recognition of national measurement standards arrangement prepared in conjunction with the National Metrology Institutes (NMIs). This arrangement also includes the recognition of calibration and measurement certificates issued by these institutes. Then, the consequences of this arrangement for trade are described. The case of chemical analysis is illustrated by the application of the Kyoto protocol on the reduction of greenhouse gases. But the global workload to be taken up by the International Committee of Weights and Measures, its Consultative Committee for Amount of Substance and the NMIs is huge.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 14 (1974), S. 3-14 
    ISSN: 1432-0827
    Schlagwort(e): Hydroxyapatite ; Mineral ; Phase ; Chemistry ; Synthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: 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.
    Kurzfassung: 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.
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 7 (1971), S. 150-162 
    ISSN: 1432-0827
    Schlagwort(e): Uranium ; Bone ; Distribution ; Fission ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: 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.
    Kurzfassung: 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.
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 54-72 
    ISSN: 1432-0827
    Schlagwort(e): Morphology ; Glycosaminoglycans ; Cartilage ; Chemistry ; Audioradiography ; Healing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: 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.
    Kurzfassung: 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.
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 228-236 
    ISSN: 1432-0827
    Schlagwort(e): Skin ; Calcinosis ; Keratin ; Chemistry ; X-ray diffraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: 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.
    Kurzfassung: 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.
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 304-319 
    ISSN: 1432-0827
    Schlagwort(e): Chemistry ; Calcium ; Phosphate ; Solubility ; Computer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: 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.
    Kurzfassung: 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.
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 10 (1972), S. 171-197 
    ISSN: 1432-0827
    Schlagwort(e): Amorphous ; Crystalline ; Calcium phosphate ; Chemistry ; Composition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: 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.
    Kurzfassung: 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.
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 23 (1977), S. 39-44 
    ISSN: 1432-0827
    Schlagwort(e): Dental cementum ; Collagen ; Protein ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Cyanogen bromide (CNBr) peptides were prepared of the insoluble collagen of bovine dental cementum. Following chromatographic separation, the peptides were identified by their amino-acid composition. Type I collagen ([α1(I)]2α2) accounted for more than 90% of the organic matrix, while Type III collagen ([α1(III)]3) was present at a level of approximately 5%. Amino-acid analyses revealed that the CNBr peptides from α1(I) and α2 chains of cementum closely resembled the corresponding peptides from calf skin. The only systematic difference was a higher level of hydroxylation of prolyl and lysyl residues of the cementum peptides.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 23 (1977), S. 87-94 
    ISSN: 1432-0827
    Schlagwort(e): Calcium ; Osteoporosis ; Lactation ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The calcium homeostatic mechanism was challenged in adult female rats by feeding them a calcium-deficient diet containing oxalate, and by subjecting them to pregnancy and lactation. The regimen caused a substantial weight loss, especially in those animals which reared their young well. Severe hypocalcaemia was observed in the lactating rats. Serum-P was slightly elevated. The content of hydroxyproline in serum was considerably elevated, reflecting the degree of calcium deprivation. Serum proteins were least influenced. The calcium depriving regimen reduced the growth of long bones, but did not stop it. The ash content of the bones was considerably reduced, the degree of reduction depended on the degree of calcium deprivation. Ash as percentage of total bone organ was reduced, but not to the same extent as total ash. Analyses of different parts of femur showed that the proximal and distal parts had lost more bone mineral than the diaphyseal shaft. The ash content of cortical bone tissue from the femur was estimated by a volumetric method. No differences were observed between test groups and controls, indicating that no measurable amounts of bone mineral had been removed from the walls of the vascular canals or by osteocytic osteolysis. Planimetric determinations on cross sections from femora disclosed that a great amount of bone had been removed from the endosteal surface of the diaphysis, while the periosteal surface demonstrated reduced bone apposition.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 197-210 
    ISSN: 1432-0827
    Schlagwort(e): Fluorescence ; Calcium ; Collagen ; Chemistry ; Bone ; Dentine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: 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.
    Kurzfassung: 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.
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 12 (1973), S. 125-136 
    ISSN: 1432-0827
    Schlagwort(e): Mineralization ; Molt ; Isopod ; Chemistry ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: 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.
    Kurzfassung: 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.
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 13 (1973), S. 259-270 
    ISSN: 1432-0827
    Schlagwort(e): Fluorapatite ; Exchange ; Chemistry ; Crystallography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: 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.
    Kurzfassung: 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.
    Notizen: 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.
    Materialart: Digitale Medien
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  • 24
    ISSN: 1432-0827
    Schlagwort(e): Bacterial amphophile ; Purification ; Chemistry ; Resorption ; Ca influx ; Cyclic AMP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The bone resorptive factor and amphipathic antigen (AcA) previously identified by us in preparations fromActinomyces viscosus have been partially purified, characterized chemically, and compared. They elute at the same location on chromatography with Ac 22. The fatty acid composition of AcA and the bone resorptive factor is the same. Some differences in carbohydrate composition are observed. TheActinomyces factor does not affect calcium influx or cyclic AMP in isolated bone cells. Therefore it is concluded that AcA stimulates resorption either by gaining entrance into bone cells or by way of a yet undetermined second messenger.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 167 (1990), S. 145-154 
    ISSN: 1432-1351
    Schlagwort(e): Moth ; Flight ; Migration ; Kinematics ; Aerodynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Air speeds and wing kinematics were determined for the Neotropical moth Urania fulgens in natural migratory flight over Lake Gatun, Republic of Panama. Morphological parameters are presented for the same insects filmed in free flight. A quasi-steady aerodynamic analysis was used to show that unsteady mechanisms of lift generation are probably not necessary to produce the forces necessary for fast forward flight. Mechanical power requirements of forward flight were estimated from the biomechanical and morphological data. Over an airspeed range of 1.5 to 4.5 m/s, the mechanical power required to fly is predicted to increase dramatically with forward speed. A comparison of estimated metabolic rates with endogenous lipid reserves suggests that U. fulgens feeds extensively on flower nectar during migration from Central into South America.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 108 (1976), S. 159-166 
    ISSN: 1432-072X
    Schlagwort(e): Non-legume ; Trema sp. ; Rhizobium ; Nodule ; Structure ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The structure of the nodules formed by Rhizobium on the non-legume Trema cannabina var. scabra was studied using the light microscope. The overall features of the nodules showed greater resemblance to the non-legume rather than the legume nodule. Nodule squashes yielded bundles of “infection threads” and “bacteroids” with morphological differences from rhizobial cells grown on yeast-mannitol-glucose agar. Two types of cell infection occurred within the bacterial zone; plant cells were either, like legumes, filled with rhizobia released from the infection threads (less than one third of infected cells) or were filled with the extensive growth and development of the “infection thread”. The rate of nitrogen fixation in the Trema nodule was high. It seemed that host cells filled with threads were active in N fixation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 164 (1995), S. 420-427 
    ISSN: 1432-072X
    Schlagwort(e): Key words Transmission electron microscopy ; Light microscopy ; Triacylglycerols ; Streptomyces ; Sudan black B
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Triacylglycerol is accumulated by Streptomyces spp. when grown in submerged culture. Ultrastructural studies using transmission electron microscopy (TEM), staining and freeze-fracture/freeze-etch procedures, and light microscopy confirmed the accumulation of neutral lipid by S. lividans and S. coelicolor during the stationary phase and its storage within membrane-bound globular structures within the cytoplasm. These structures were of various sizes and occupied up to approximately 80% of the total cell volume at that time. There was no evidence of such material within cells examined during the early exponential phase of growth. The globules visualised by TEM were electron-transparent since they comprised lipids containing saturated fatty acids that did not react with osmium tetroxide. The globules appeared to be bounded by a single membrane.
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Astrophysics and space science 224 (1995), S. 81-84 
    ISSN: 1572-946X
    Schlagwort(e): Chemistry ; Depletions ; Shocks ; IRAS 05338-0624 ; NGC 1333 IRAS 4
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract High resolution interferometer and single-dish observations of young, deeply embedded stellar systems reveal a complex chemistry in the circumstellar environments of low to intermediate mass stars. Depletions of gas-phase molecules, grain mantle evaporation, and shock interactions actively drive chemical processes in different regions around young stars. We present results for two systems, IRAS 05338-0624 and NGC 1333 IRAS 4, to illustrate the behavior found and to examine the physical processes at work.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Astrophysics and space science 216 (1994), S. 153-154 
    ISSN: 1572-946X
    Schlagwort(e): Chemistry ; Molecular Hydrogen ; Cloud Models
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Boundary layer meteorology 85 (1997), S. 197-222 
    ISSN: 1573-1472
    Schlagwort(e): Turbulence ; Chemistry ; Closure ; Convective boundary layer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract We study the interactions of chemistry and turbulent mixing of tracersin the convective boundary layer with a second-order closure model,including higher order chemistry terms. In order to limit the number of predictive equations we prescribe the profiles for ¯w¯Θ, ¯w¯θ ¯θ and the lengthscale l. However, for model validation we treat temperature and humidity asinert tracers, and compare the results with profiles observed during theAir Mass Transformation Experiment, and with similarity expressions for thesurface layer. We find good agreement of the mean profiles, but the (co-)variances are slightly underpredicted. Furthermore, the model usesdiagnostic equations expressing third moments of concentration in terms ofsecond moments and their vertical derivatives. They are compared withlarge-eddy model results, showing good agreement and, therefore, thesimplifications are justified. The model is applied to the transport of two gases subject to one bimolecular reaction. The importance of concentration correlations on themean transformation rate is studied. For two gases diffusing in oppositedirections we find for moderate and fast chemistry a 50% and90% decreased transformation rate due to the negatively correlatedconcentrations. These values are similar to large-eddy results of Schumannand Sykes et al. For two bottom-up tracers we find that the covariance ofboth reactive species is either positive or negative, increasing or reducingthe effective transformation rate depending on the Damköhler number (the ratio of the turbulent and the chemistry timescale). A significantdirect influence of chemistry on the flux divergence is found in bothcases. According to the model the effective transport to mid-levels of theboundary layer is increased when two reactive tracers diffuse in oppositedirections, and decreased in the case of two bottom-up tracers.
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 24 (1986), S. 1-24 
    ISSN: 1432-1416
    Schlagwort(e): Aerodynamics ; Pollination ; Ephedra ; Computer simulations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Computer simulations are used to predict the behavior of pollen grains with different physical properties within the acceleration field created around the ovules of the gymnosperm Ephedra trifurca. A modelling procedure is given that (1) calculates the number of pollen grains captured by an ovule's pollination-droplet and (2) gives a correlation between pollination efficiency and the physical properties (= mass, size) of different types of pollen. Based on this procedure, the number of Ephedra pollen grains captured by micropyles can be less than the number captured from other species. However, the mass and size of Ephedra pollen grains appear to coincide with those predicted to yield a local maximum of pollination efficiency, i.e. slightly larger or smaller values of either mass or size would decrease the probability of capture. In addition, the properties of Ephedra pollen grains operate synergistically in the aerodynamic environment around ovules and are focused to collide with pollination-droplets. By analogy, the properties of Ephedra pollen coincide with those predicted for a localized “adaptive peak”. The physical properties of pollen grain types other than E. trifurca that can maximize pollen capture are not generally represented in the aerobiology of Ephedra during the pollination season. Therefore, the phenology of pollen release, community taxonomic-composition, and the physics of particle capture play collectively important roles in the reproductive success of Ephedra trifurca.
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 121 (1971), S. 377-441 
    ISSN: 1432-0878
    Schlagwort(e): Visual system ; Insects diptera ; Lamina ganglionaris ; Optic cartridges ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The structure of optic cartridges in the frontal part of the lamina ganglionaris (the outermost synaptic region of the visual system of insects) has been analysed from selective and reduced silver stained preparations. The results, obtained from studies on five different species of Diptera, confirm that six retinula cells, together situated in a single ommatidium, project to six optic cartridges in a manner no different from that described by Braitenberg (1967) from Musca domestica. Each optic cartridge contains five first order interneurons (monopolar cells) which project together to a single column in the second synaptic region, the medulla. The dendritic arrangement of two of these neurons (L1 and L2) indicates that they must make contact with all six retinula cell terminals of a cartridge (R1–R6). Two others (L3 and L5) have processes that reach to only some of the retinula cell endings. A fifth form of monopolar cell (L4) sometimes has an arrangement of processes which could establish contact with all six retinula cells: other cells of the same type may contact only a proportion of them. This neuron (L4) also has an arrangement of collaterals such as to allow lateral interaction between neigbouring optic cartridges. The processes of the other four monopolar cells (L1, L2, L3 and L5) are usually contained within a single cartridge. In addition to these elements there is a pair of receptor prolongations (the long visual fibres, R7 and R8) that bypasses all other elements of a cartridge, including the receptor terminals R1–R6, and finally terminates in the medulla. Four types of neurons, which are derived from perikarya lying just beneath or just above the second synaptic region, send fibres across the first optic chiasma to the lamina. Like all the other interneuronal elements of cartridges the terminals of these so-called “centrifugal” cells have characteristic topographical relationships with the cyclic arrangement of retinula cell terminals. Apart from the above mentioned neurons there is also a system of tangential fibres whose processes invade single cartridges but which together could provide a substrate for relaying information to the medulla derived from aggregates of cartridges. Optic cartridges contain at least 15 neural elements other than retinula cells. This complex structure is discussed with respect to the receptor physiology, as it is known from electrophysiological and behavioural experiments. The arrangements of neurons in cartridges is tentatively interpreted as a means of providing at least 6 separate channels of information to the medulla, four of which may serve special functions such as relaying color coded information or information about the angle of polarised light at high light intensities.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 126 (1972), S. 518-535 
    ISSN: 1432-0878
    Schlagwort(e): Vital staining ; Fibroblasts ; Autophagic vacuoles ; Influence of fixatives ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Fibroblastenkulturen wurden mit Mepacrin (Atebrin®), Neutralrot und Toluidinblau unter vergleichbaren Bedingungen vitalgefärbt. Die Farbstoffe induzieren die Bildung autophagischer Vakuolen (Autolysosomen) im Cytoplasma. Die Eignung von sieben verschiedenen Fixantien zur Erhaltung dieser im lichtmikroskopischen Sinn neugebildeten Strukturen wurde untersucht. Kriterien der jeweiligen Fixationsleistung waren einmal die Erhaltung der autophagischen Vakuolen an sich, zum anderen die Erhaltung ihrer farbstoffabhängigen, morphologischen Individualität. Als wenig leistungsfähig haben sich erwiesen die Lösungen nach Carnoy und Bouin sowie Formol. Glutaraldehyd bewahrt die Lysosomenstruktur befriedigend, jedoch nicht ausreichend stabil für weitere, etwa histochemische, Eingriffe. Kaliumbichromat gewährleistet bessere Stabilität, jedoch nur geringe Lebensähnlichkeit der Autolysosomen. OsO4 und NaMnO4 sind den anderen Fixantien hinsichtlich der Erfüllung beider Kriterien deutlich überlegen. Die Befunde werden mit dem lipidstabilisierenden Effekt, den beide Metalloxydverbindungen an den phospholipidreichen Autolysosomen ausüben, in Zusammenhang gebracht. Unterschiede in der Wirkung ließen sich nach Anwendung von OsO4 und NaMnO4 an den AV nachweisen: Mepacrin-AV werden durch OsO4 etwas lebensähnlicher erhalten als durch NaMnO4. Die Neutralrot-AV und Toluidinblau-AV mit deutlicher vakuolärer Struktur werden nur durch Permanganat im Zusammenhang erhalten, mit deutlicher Abgrenzung der Toluidinblau-induzierten von den Neutralrot-induzierten Autolysosomen. Nach Osmium- und Permanganatfixation zeigen die Zellkulturen starke Affinität zu Methylenblau, nicht Eosin. Nur die OsO4-fixierten Autolysosomen halten gegenüber Alkoholeinwirkung ihre Anfärbung im wesentlichen bei. Die Befunde werden diskutiert.
    Notizen: Summary Fibroblasts grown in monolayer were subjected to vital staining by mepacrine (Atebrine®), neutral red and toludine blue under comparable conditions. These dyes induce the formation of autophagic vacuoles (autolysosomes) in the cytoplasm. The preservation of these structures, which are considered to be newly formed in the dimension of the light microscope, by seven different fixatives has been examined. The criteria employed to assess the performance of each fixative consisted of 1. the preservation of the autophagic vacuoles per se and 2. their dye-dependent morphological characteristics. Fixation by Carnoy's or Bouin's solution as well as by formaline gave poor results. Glutaraldehyde preserved lysosomal structure satisfactorily, but not adequately for further application of histochemical methods. Potassium dichromate has a stabilizing effect on autophagic vacuoles, however, structures are not equivalent to those observed in living cells. Osmium tetroxide (OsO4) and sodium permanganate (NaMnO4) are superior to the other fixatives with regard to the afore mentioned criteria. These observations are explained by the wellknown lipid-stabilizing effect which both metal oxides are expected to exert on autolysosomes with their high content of phospholipids. After fixation with OsO4 and NaMnO4 diverging effects on autophagic vacuoles could be ascertained. Mepacrine-induced autophagic vacuoles are preserved somewhat more accurately by OsO4 than by NaMnO4. Autolysosomes induced by neutral red and toluidine blue display a more vacuolated appearance and are preserved as a whole only by permanganate. Distinct differences exist between autophagic vacuoles induced by toluidine blue and those induced by neutral red. After fixation by OsO4 and NaMnO4 cells from culture display a strong affinity to methylene blue, but not to eosin. The staining of autolysosomes by methylene blue is resistant to ethanol after fixation in OsO4 only. The results are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 130 (1972), S. 378-388 
    ISSN: 1432-0878
    Schlagwort(e): Arteries ; Children ; Structure ; Pattern of calcification ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Gross calcifications of the common iliac and internal iliac arteries represent a common finding in newborn children and infants. In both arteries, the calcific deposits regularly appear in certain areas of the arterial luminal surface only, whereas the other parts of the arterial wall remain free of gross lesions even in cases with a pronounced calcification. In the common iliac artery, the lateral wall of the vessel and the adjacent sectors of the anterior and posterior wall represent the predilection site of calcific deposits. In the internal iliac artery, the gross calcifications have been regularly demonstrated in the dorso-medial wall. The predominant localisation of the calcification in these parts of the vessels and its absence in the others depend on the definite structural features of the arterial tube and different affinity for calcium of the individual structural elements. In both iliac arteries, only the primary internal elastic membrane undergoes early calcification. However, unlike the most muscular arteries, this membrane is not developed in the whole arterial circumference of the common iliac and internal iliac arteries, but is absent in large areas of their arterial luminal layer. In these areas, the subendothelial or subintimal elastic layers are formed by the networks of longitudinally arranged elastic fibers or membraneous elastic structures which arise from the elastic networks with the further growth. These elastic elements always stay free of calcific deposits. The structural features found in both iliac arteries may be important for the development of the later pathological changes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 129 (1972), S. 533-547 
    ISSN: 1432-0878
    Schlagwort(e): Epiphysis ; Circumventricular structures of the epithalamus ; Elephant ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die dorsale Wand des Epithalamus des Elefanten enthält zwei Aussackungen, den langen Recessus suprapinealis (RS), der mit Plexus chorioideus gefüllt ist, und den kurzen breiten Recessus pinealis (RP). Die dickeren Wandpartien beider Recessus bestehen überwiegend aus Pinealgewebe mit Pinealocyten. Das Ependym des Epithalamus bildet an fünf Orten circumventrikuläre Strukturen (CS); drei dieser CS gehören zum Subcommissuralorgan. Das Ependym mit der höchsten Aktivität liegt auf der unteren Lippe und in den spitzen lateralen Hörnern des RP. Dieses Epithel trägt Kinocilien und besitzt Zellprotrusionen; es ist mäßig gomoripositiv. Über die Verteilung der verschiedenen Kennzeichen der CS-Strukturen gibt eine Tabelle Auskunft. In der lateralen Wand des Epithalamus unter der Commissura habenularis liegen die Verrucae epithalami, die unterschiedlich tiefe ependymbedeckte Spalten besitzen. Die mögliche funktionelle Bedeutung dieser Strukturen wird kurz erörtert.
    Notizen: Summary The dorsal wall of the epithalamus of the elephant has two evaginations: the long recessus suprapinealis (RS) filled with plexus chorioideus and the short and wide recessus pinealis (RP). The thick part of the wall of both recessus consists mainly of pineal tissue with pinealocytes. The ependyma of the epithalamic region has about 5 loci with circumventricular formations (CS), three of them belonging to the subcommissural organ. The ependyma with equivalents of high activity is situated in the lower lip and in the lateral tapering corners of the RP. This epithelium bears kinocilia and shows protrusions of the cells extending into the ventricle, it is fairly gomoripositive. Details concerning the structural differences in the various loci of CS are described. There are some verrucae epithalami in the lateral wall of the epithalamus below the commissura habenularis having more or less deep clefts covered with ependyma. The possible functions of these structures are briefly discussed.
    Materialart: Digitale Medien
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 415-438 
    ISSN: 1432-0878
    Schlagwort(e): Brain stem ; Human ; Dorsal glossopharyngeus vagus-complex ; Lipofuscin ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Mit Hilfe einer neu entwickelten Methode zur Darstellung von Neurolipofuscinen wird das Pigmentbild des dorsalen Glossopharyngeus- und Vagusgebietes beschrieben. Da außer wenigen elastischen Fasern nur die Lipofuscingranula, welche in Nervenzellen gespeichert sind, angefärbt werden, können Schnitte bis zu einer Dicke von 800 μ verwendet werden. Sie lassen bei stereomikroskopischer Betrachtung die Grenzen von Kerngebieten meist deutlich erkennen, da durch die Übereinanderprojektion zahlreicher Neurone auch geringe Unterschiede in der Dichte der Zellen, sowie in der Art und dem Ausmaß ihrer Pigmentierung hervortreten. Das dorsale Glossopharyngeus- und Vagusgebiet wird in elf Kerne unterteilt. Seinen caudalen Pol bilden der Nucleus terminalis caudalis alae cinereae, der Nucleus commissuralis und parvocellularis. Im mittleren Bereich liegen zahlreiche Kerne von kennzeichnender Gestalt nahe beieinander. Der Nucleus pigmentosus nervi vagi hüllt das Gesamtgebiet ein und füllt die Räume zwischen den Kernen aus. Der Nucleus alaris nervi vagi durchzieht als breite Zellplatte den ganzen mittleren Teil. Seine großen Neurone speichern Lipofuscinkörnchen nicht nur in den Perikaryen sondern auch in Form langer Pigmentspindeln in den Dendriten. Im kleinzelligen Gebiet lateral vom alaren Kern werden ein Nucleus terminalis intermedius alae cinereae, der Kern der Area postrema, ein Nucleus tractus solitarii, ein Nucleus gelatinosus, sowie ein oraler Terminalkern der Ala cinerea voneinander unterschieden. In allen Terminalkernen findet sich reichlich Dendritenpigment neben den kräftig gefärbten Lipofuscinkegeln in den Zelleibern. An der Grenze zum oralen Abschnitt des Gesamtgebietes vermindert sich die Dichte der Pigmentierung. Hier liegt in der Fortsetzung des alaren Vaguskernes der Nucleus salivatorius inferior. Eine so weitgehende Untergliederung des Glossopharyngeus- und Vagusgebietes steht in Widerspruch zu den Darstellungen zahlreicher Autoren. Vor allem im kleinzelligen Bereich, der meist als ein einheitliches Areal aufgefaßt wird, können mit Hilfe der Pigmentarchitektonik die drei Terminalkerne der Ala cinerea eindeutig vom eigentlichen Kern des Solitärbündels und vom Nucleus gelatinosus unterschieden werden. Außerdem stellt sich heraus, daß die Gesamtheit der melaninhaltigen Neurone im Vagusgebiet, zusammen mit einem weiteren großen Zelltyp, der reichlich mit Lipofuscin beladen ist, ein eigenes kompliziert geformtes Kerngebiet bilden, das sicher von den übrigen Kernen, auch von dem gleichfalls großzelligen Nucleus alaris abgetrennt werden kann.
    Notizen: Summary By means of a newly developed method for the demonstration of neurolipofuscines the distribution of pigments in the dorsal glossopharyngeus-vagus-complex is described. Since apart from few elastic fibers only the lipofuscin granules which are stored in neurons are stained, sections up to 800 μ can be investigated. Under the stereomicroscope they show in general clearly the borders of nuclei, since because of the superposition of numerous neurons also slight differences in respect of the density of the cells and type and extent of their pigmentation show up clearly. The dorsal glossopharyngeus-vagus-complex of the human is subdivided into eleven nuclei. Its caudal pole is formed by the nucleus terminalis caudalis alae cinereae, the nucleus commissuralis and parvocellularis. In the middle portion several nuclei of characteristic shape lie closely together. The nucleus pigmentosus nervi vagi envelopes the whole complex and fills the spaces between the nuclei. The nucleus alaris nervi vagi forms a broad plate of cells extending over the whole length of the middle portion. Its large neurons do not only store the lipofuscin granules in their perikarya but also in form of elongated pigment spindles in the dendrites. In the parvicellular parts lateral of the nucleus alaris a nucleus terminalis intermedius alae cinereae, a nucleus of the area postrema, a nucleus tractus solitarii, a nucleus gelatinosus, and a nucleus terminalis oralis alae cinereae are to be distinguished. In all terminal nuclei abundant pigment spindles of the dendrites occur beside the heavily stained lipofuscin pyramids in the perikarya. At the border of the oral part of the complex the density of pigmentation decreases. Here, in continuity of the nucleus alaris, the nucleus salivatorius inferior is situated. Such an extensive subdivision of the glossopharyngeus — vagus-complex of the human is in contrast to the description of numerous authors. Especially in the parvicellular part, which generally is described as a uniform area, by means of pigment architecture unequivocally the three terminal nuclei of the ala cinerea can be distinguished from the nucleus tractus solitarii proper and the nucleus gelatinosus. In addition it becomes apparent by the pigment architecture that the whole population of melanin containing neurons in the vagus-complex, together with a further large cell type, which stores vast amounts of lipofuscin granules, forms a distinctive nucleus which can be separated with certainty from the other nuclei, as well as the equally magnocellular nucleus alaris.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 139 (1973), S. 179-200 
    ISSN: 1432-0878
    Schlagwort(e): Retino-preoptic pathway ; Optic tracts ; Rana temporaria ; Light microscopy ; Autoradiography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The optic tracts and centres of optic terminals of Rana temporaria have been investigated with silver impregnation techniques after unilaterally cutting the optic nerve and autoradiographically after injection of a mixture of tritiated amino acids into the vitreous body of the left eye. The observations on the course of the optic tracts and on the optic terminals in the thalamus and optic tectum are to a great extent in agreement with those of other authors. The probability of a retino-preoptic pathway is supported by the detection of fibres running in dorsal direction in front of the place where the optic nerve penetrates the brain. In horizontal sections these fibres can be seen deviating from the optic tract, covering a short distance in frontal direction and then turning upward under an angle of about 90 degrees. They disappear between the ventral aldehyde-fuchsin positive cells of the preoptic nucleus. The ventral and median parts of the ipsilateral preoptic nucleus contain fragments of degenerated fibres. Autoradiographic data are also in favour of the presence of an ipsilateral retino-preoptic tract. After carefully counting the number of grains over left and right preoptic nucleus, it appeared that over the ventral and median parts of the left preoptic nucleus more grains occur than over the identical areas of the right one.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 139 (1973), S. 473-485 
    ISSN: 1432-0878
    Schlagwort(e): Pineal gland ; Rabbit ; Architecture ; Autonomic innervation ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A light microscopic investigation of the rabbit pineal gland with the aid of silver-stained sections gave the following results. In the gland a medulla and a cortex can be distinguished, the medulla containing so-called light and dark pinealocytes, the cortex only light ones. Autonomic nerve fibres reach the pineal organ by two routes: (1) via the perivascular spaces of pineal blood vessels and (2) via two distinct nerve bundles, the nervi conarii. Bilateral superior cervical ganglionectomy revealed that these pinealo-petal nerve fibres are mainly orthosympathetic postganglionic. Intramural pineal neurones with synaptic-like structures on their cell bodies and dendrites point to the presence of a parasympathetic innervation next to the orthosympathetic one. Direct afferent or efferent neural connections with the brain appeared to be absent.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 138 (1973), S. 63-73 
    ISSN: 1432-0878
    Schlagwort(e): Adenohypophysis ; Rat ; Gonadotrophic cells ; Cycle, influence of testosterone ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 4-day cyclic adult female Wistar rats were injected subcutaneously with testosterone propionate on diestrus 1 at 16:00 and on diestrus 2 at 10:00 respectively. Non-injected females served as controls. Autopsy was performed on diestrus 2 at 23:00, and on proestrus at 14:00 and 17:00 respectively. The blue Alcian-PAS staining was used to evidence FSH (β) and LH (γ) pituitary cells. In control animals and in diestrus 2 injected females only a small number of FSH cells could be detected on diestrus 2 at 23:00. This number increased markedly on proestrus at 14:00 and decreased on proestrus at 17:00. A similar evolution was observed in diestrus 1 testosterone injected females, but the number of FSH cells appeared higher at any stage of autopsy in these females than in diestrus 2 injected females and in control rats. In control females, numerous LH cells were observed on diestrus 2 at 23:00. The number of these cells was diminished on proestrus at 14:00 and still more at 17:00. On the contrary few LH cells were detected in testosterone injected females on the evening of diestrus 2. An increase of these cells occurred on proestrus at 14:00, followed at 17:00 by only a weak diminution as established by comparison with control animals. An inhibition of FSH release and a suppression of the proestrus surge of LH were therefore supposed to cause, on one hand, the slowing up of follicular growth observed in diestrus 1 injected females and, on the other hand, the blockage of ovulation noted in both diestrus 1 and diestrus 2 treated animals.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 40
    ISSN: 1432-0878
    Schlagwort(e): Hippocampal region (rat) ; Distribution of dehydrogenases ; Postnatal development ; Histochemistry ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Succinate-, α-glycerophosphate-, NADH-, and NADPH dehydrogenases (tetrazolium reductases) were studied histochemically in brain sections. The distribution of these enzymes in the hippocampal region was mapped in different postnatal stages. In addition to the hippocampus and the dentate area which have also been dealt with by other authors, the description includes the entorhinal area, parasubiculum, presubiculum, and subiculum. In all the areas of the hippocampal region the enzyme activity is first localized mainly in cell bodies. Activity in the neuropil shows a tendency to increase with age throughout the stages studied. Examples of particularly early or late differentiation of the histochemical pattern exist. Thus already after 4–6 days the differentiated staining pattern in the hippocampal layers as seen in the adult, begins to appear. In the entorhinal area the early enzyme distribution agrees with that in the adult and facilitates identification of its layers. After 22 days the fundamental enzyme chemoarchitectonics of the adult rat brain has been obtained. Histochemical characteristics of the different areas, support the view that the hippocampal region constitutes an entity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 141 (1973), S. 375-400 
    ISSN: 1432-0878
    Schlagwort(e): Hippocampal region (rat) ; AChE distribution ; Postnatal development ; Histochemistry ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Acetylcholinesterase (AChE) in the hippocampal region was studied histochemically in different postnatal stages. Enzyme changes are described for the hippocampus proper, the dentate area, the entorhinal area, parasubiculum, area retrosplenialis e, presubiculum, and subiculum. In 1 day old animals there are only traces of AChE in solitary perikarya of the hippocampal stratum radiatum, while there is no activity in the neuropil. This is in contrast to other regions of the brain, e.g. the corpus striatum and the medial septum. Enzyme activity in the neuropil, although very weak, is seen clearly on the 2nd day. While the enzyme reaction in some cell soma seems to be permanent and also present in adult rats, other cell bodies, e.g. in the entorhinal area lose AChE activity during the last part of the 2nd week and in the 3rd week. Similar observations have been made on other parts of the central nervous system. The main features of chemodifferentiation in the hippocampal region seem to be completed by the end of the third week, although most layers and areas have not yet achieved the same high staining intensity as seen in the adult rats.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 142 (1973), S. 131-146 
    ISSN: 1432-0878
    Schlagwort(e): Epidermis (mouse) ; Pattern of organization ; Proliferation kinetics ; Three-dimensional analysis ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 1. Es wird eine Methode zur Herstellung, Montierung und Färbung von epidermalen Häutchenpräparaten zur dreidimensionalen Analyse des Epidermis-Aufbaues beschrieben. Eine Kombination mit der Histoautoradiographie ist bedingt möglich. Damit ist eine Basis für weitere Untersuchungen mit neuer Fragestellung geschaffen. 2. Die untersuchten Objekte Mäuseohr und Rückenhaut zeigen eine bisher unbekannte, auffallende Musterbildung mit Zuordnung bestimmter interfollikulärer basaler Gruppen zu Zellen des Stratum spinosum und des Stratum corneum. Es handelt sich um rosettenähnliche Gebilde aus mehreren peripheren Basalzellen und meist einer zentralen Spinosumzelle. 3. Die Bedeutung der Befunde für die normale wie für die pathologische Regeneration und Neoplasie der Epidermis ist offen. Es werden Beziehungen zum Regenerationsmodus und damit zur Proliferationskinetik der Epidermis diskutiert. In diesem Zusammenhang sind die Untersuchungen auch für die Humanpathologie relevant.
    Notizen: Summary 1. A method for the preparation, mounting, and staining of thin preparations of mouse epidermis is described, which allows a three-dimensional analysis of epidermal structure. A limited combination of this technique with histo-autoradiography is possible, thereby presenting a broader basis for further investigations. 2. Both ear and back skin show a striking, previously unrecognized pattern of organization, in which definite interfollicular basal cell groups are oriented towards cells of the stratum spinosum and stratum corneum. A rosettelike picture of many peripheral basal cells and, in most instances, a central spinosum cell is found. 3. The significance of our findings for normal and pathological regenerations as well as neoplasia of the epidermis remains open. We discuss relationships to the mode of regeneration and thus the kinetics of proliferation in the epidermis. Our investigations are also relevant for human pathology in this regard.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 148 (1974), S. 347-358 
    ISSN: 1432-0878
    Schlagwort(e): Pituitary, catfish ; Cell-types ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Seven distinct types of secretory cell can be differentiated in the pituitary gland of the fresh-water catfish, Heteropneustes fossilis. The presumptive prolactin cells appeared completely degranulated. Corticotrophs and thyrotrophs were identified by their response to metopirone and β methasol or to thiourea and thyroxine respectively. A single gonadotrophic cell type was identified, which showed a progressive increase in nuclear size, cell size and cytoplasmic granulation related to vitellogenesis in the ovary. Presumptive somatotrophs did not react to any of the experimental treatments used. In the pars intermedia, one of the two cell types — the PbH+ cells — showed an increase in activity in response to metopirone, thyroxine and reserpine; the PAS+ cells in this region remained relatively inactive.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 144 (1973), S. 573-583 
    ISSN: 1432-0878
    Schlagwort(e): Gills ; Tilapia mossambica ; Blood vessels ; Arteriovenous anastomoses ; Light microscopy ; Quantitative evaluation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The non-respiratory vascular system of T. mossambica gill filaments was studied in serial longitudinal and cross sections. Comparatively few scattered vascular communications occur between the afferent filament artery and the central venous sinus (AVAaff). The efferent filament artery, however, is connected by regularly arranged anastomoses (AVAeff), directly, and sometimes indirectly via nutritive vessels, to the central sinus. These AVAeff are about as numerous as lamellae counted on one side of each filament, although they diminish slightly in number towards the filament base. The relation AVAeff to AVAaff was 17.6:1 in the distal and 17.8:1 in the basal filamental region, while in the tip region of 7 filaments 126 AVAeff but only 1 AVAaff were encountered. No direct connection between the lamellar lacunae and the central sinus was detected. According to these results, non-respiratory intrafilamental blood shunting appears unlikely. AVAeff are assumed to be the main route for blood entering the central venous sinus which would consequently flow into the branchial veins.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 45
    ISSN: 1432-0878
    Schlagwort(e): Entorhinal area ; Guinea pig ; Subdivision ; Distribution of heavy metal ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The boundary line dividing the entorhinal area into a pars medialis and a pars lateralis has been determined in adult guinea pig by comparison of graphic maps of the distribution of heavy metals and of the terminal field of a presubiculum → entorhinal area projection. The virtual coincidence of the histochemically and hodologically based subdivisions strongly supports the assumption that the obtained boundary line represents the true location of a functional limit between the two entorhinal parts.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 151 (1974), S. 219-228 
    ISSN: 1432-0878
    Schlagwort(e): Cell death ; Central nervous system ; Embryogenesis of Calliphora (Insecta) ; Vital staining ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary During the late embryonic period, cell death occurs in the central nervous system of Calliphora erythrocephala. The degenerating cells are small and rounded, contain a pyknotic nucleus, and selectively accumulate basic vital dyes such as nile blue sulphate and acridine orange. The number of degenerating cells is highest 13–15 hours after oviposition and decreases during the shortening of the ventral nerve cord. Nevertheless, these degenerating cells do not represent a morphogenetic phenomenon, since their number is too small to account for the 55% decrease in the length of the ventral nerve cord. In all probability the pyknoses seen in the central nervous system of this holometabolic insect are to be interpreted as phylogenetic degenerations of clearly vestigial neuroblasts that have lost functions they might have retained in the larvae of insects in lower orders, for instance the innervation of legs, wings, a larger number of abdominal segments, etc. About half of the pyknoses occur in pairs.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 161 (1975), S. 431-444 
    ISSN: 1432-0878
    Schlagwort(e): Actin ; Fluorescent heavy meromyosin ; Non-muscle cells ; Motility ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An improved technique for fluorescent labelling of heavy meromyosin has made it possible to detect on a light microscopic level the cellular sites of actin localization. Rabbit heavy meromyosin (HMM) was labelled with fluorescein isothiocyanate so that the actin binding site was protected during the reaction. The specificity of fluorescent HMM binding to cellular actin was tested by using glycerinated myofibrils. Staining was most intense in the I-Bands, and decreased at the edges of the A-Band, where actin filaments overlap with myosin. No staining occurred in the H-Zones or in the Z-Bands. The fluorescent HMM could be removed by washing with a relaxing solution. Similar sarcomeric patterns were obtained when embryonic chick skeletal and cardiac muscle cells were stained with fluorescent HMM. Localized fluorescent staining was also observed in smooth muscle fibers, axons and growth cones of nerves, acrosomal caps of sperm, cleavage furrows of dividing cells and pseudopods of various motile cells, all of which are known to contain actin. In sessile cells, the actin was found predominantly in fibrous bundles. This pattern of actin localization was altered when the cells underwent cleavage or became motile. The relationship between the intracellular distribution of actin and its function in the cell is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 175 (1976), S. 131-135 
    ISSN: 1432-0878
    Schlagwort(e): Gut epithelium ; Ciona intestinalis ; Argyrophilia ; Argentaffinity ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Argyrophilic and argentaffin cells occur in the stomach and intestinal epithelium of the sea-squirt, Ciona intestinalis L.. These cells are characterized by their basal swelling which contains the nucleus surrounded by small secretory granules and by a filamentous cell-apex which reaches the gut lumen. The cells are scattered unevenly within the epithelium. Their number decreases rapidly towards the lower part of the intestine. The localization, size of granules and their shape are features which differentiate these cells from other secretory cells in the gut epithelium such as mucous cells. These cells are thought to possess an endocrine function.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 168 (1976), S. 33-43 
    ISSN: 1432-0878
    Schlagwort(e): Human fetal pancreas ; Endocrine cells ; Argyrophil reactions ; Light microscopy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The endocrine cells in the pancreas of five human fetuses with gestational ages of 18–20 weeks were examined by light and electron microscopy with special regard to argyrophil reactions. B-cells and typical A and D-cells were easily identified electron microscopically on the basis of their typical secretory granules. In the Grimelius argyrophil silver stain, a concentration of silver grains over the less electron dense peripheral mantle of the A-cell secretory granules was observed by electron microscopy. In the Hellerström and Hellman modification of the argyrophil Davenport alcoholic silver stain, silver grains were concentrated over the internal structures of the D-cell secretory granules. With this stain an accumulation of silver grains was also seen at the surface of the A-cell secretory granules. The argyrophil reaction of the A-granules was less pronounced than in the D-cells. In addition to B-cells and A- and D-cells, two other types of endocrine cell were observed by electron microscopy. These cells were argyrophil with the silver impregnation method of Grimelius. The electron microscopic findings at least partly explain the frequent overlapping between the two staining methods observed at the light microscope level.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 141 (1973), S. 493-503 
    ISSN: 1432-0878
    Schlagwort(e): Pituitary ; Glomerular body ; Marine teleost ; Hexagrammos otakii ; Larval osmoregulation ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the larvae of the marine teleost, Hexagrammos otakii, the prolactin, ACTH, STH and pars-intermedia cells as well as the neurohypophysis and glomerular body showed no histological change at the time of hatching. These cells or organs do not seem to be specifically involved in the mechanisms of adjustment to the hypertonic osmotic stress at this time. The size of the nuclei of the prolactin cells increased in fresh-water (F. W.) and that of the ACTH cells decreased in 2/3, 1/2 and 1/3 sea-water (S.W.). The amount of chrome-alum haematoxylin-positive material in the neurohypophysis of fish immersed in 1/2 S.W., 1/3 S.W. and F.W. was less than that of the control fish. There was a difference in the glomerular ratio between the fish kept in F. W. and control fish. And the red blood cells in the glomerulus of the larvae kept in 1/2 and 1/3 S.W. apparently increased in number in comparison with the control fish.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 143 (1973), S. 535-547 
    ISSN: 1432-0878
    Schlagwort(e): Adenohypophysis ; Rat ; Mitoses, topographic distribution ; Influence of fixation ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé Les mitoses de l'adénohypophyse du rat mâle ont été examinées comparativement après fixation par perfusion et après fixation par immersion. Après fixation par perfusion la répartition topographique des mitoses dans le parenchyme est homogène, et l'index mitotique est de 1,85 pour 1 000 cellules. Après fixation par immersion, la densité des mitoses décroit de la périphérie vers le centre, et l'index mitotique n'est que de 0,80 mitoses pour 1 000 cellules. La lenteur de pénétration du fixateur pendant l'immersion est tenue pour principal responsable des différences observées. Elle entraîne une modification de l'aspect des mitoses, telle que plus de la moitié d'entre elles ne sont pas identifiables et échappent aux comptages.
    Notizen: Summary The mitoses of the adenohypophysis in male rats have been observed comparatively after fixation by perfusion and fixation by immersion. After fixation by perfusion, the topographic distribution of mitoses throughout the parenchyma is homogenous and the mitotic index is 1.85 for 1 000 cells. After fixation by immersion, the density of the mitoses is decreasing from the periphery towards the center and the mitotic index is only 0.80 for 1 000 cells. The slow penetration of the fixative during fixation by immersion is considered to be the main cause in the differences observed. This slow action causes a modification in the aspect of the mitoses, and more than fifty percent of them cannot be identified and escape to the counts.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 147 (1974), S. 249-257 
    ISSN: 1432-0878
    Schlagwort(e): Chromosomes ; Action of colchicine ; Botryllus schlosseri (Ascidia) ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The course of c-mitosis in early embryos ofBotryllus schlosseri is arrested in a bizarre c-metaphase configuration in which the chromosome arms are tightly paired and sister kinetochores are well separated. This new type of c-metaphase chromosomes occurs because kinetochores are normally separated during prometaphase and sister c-chromatids tend to adhere to each other. Abnormal activity of sister kinetochores, chromosome fragmentation, adherence between chromosomes, overcondensation of chromosomes and bipolar arrangement of the c-pairs, are some additional effects induced by colchicine treatment of oocyte cleaving eggs ofB. schlosseri that have been studied. The behaviour of both normal and c-chromosomes ofB. schlosseri suggests that the forces acting upon kinetochores reach a minimum at metaphase and that they are not diminished by colchicine treatment.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 144 (1973), S. 353-368 
    ISSN: 1432-0878
    Schlagwort(e): Epidermis ; Bufo bufo ; Moulting cycle ; Structure ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Skin samples were taken from 17 toads (Bufo bufo) in various phases of the moulting cycle. The phase was determined by recording a number of moulting intervals prior to sacrifice and by study of the macroscopic appearance of the skin and the moulting behaviour at sacrifice. Eight of the toads were in the moult when the samples were taken. Characteristic morphological changes were found to be restricted to a period immediately prior to and after shedding of the slough. Chemical changes of the membranes of stratum corneum (or material adhered to them) were observed already prior to adoption of the moulting posture. The separation from the underlying epidermis prior to shedding was accompanied by a swelling of the stratum corneum cells. After final detachment of the slough the replacement layer was differentiated into a new stratum corneum within 24 hours. Significant changes in the morphology of the flask cells were not observed. The findings are discussed with emphasis on the processes of separation and differentiation of the stratum corneum. Based on the morphology of the epidermis the following terminology is proposed for the phases of the moulting cycle: Intermoult phase, preparation phase, early shedding phase, late shedding phase, and differentiation phase.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 150 (1974), S. 95-105 
    ISSN: 1432-0878
    Schlagwort(e): Mucosal mast cells ; Rat ; Compound 48/80 ; Degranulation, Release ; Light microscopy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Mast cells in the tongue and lamina propria of the duodenal mucosa, representing two cell types with different morphological, histochemical and functional properties have been studied under the electron microscope. Both cell types were found to contain similar moderately electron dense and homogeneous granules surrounded by a tight membrane constituting the basic ultrastructural characteristics of mast cells. The mucosal mast cells, however, contained fewer granules per cell and the individual granules often exhibited considerable variation in size. In addition the mucosal mast cells, unlike those of the tongue, peritoneum and skin, had a smooth plasma membrane lacking microvilli and possessed irregularly shaped or lobulated nuclei. In the tongue mast cells, administration of Compound 48/80 caused the formation of vacuoles around the granules, expulsion of granules from the cells and disintegration of the granular matrix, but no changes that could be attributed to 48/80 could be found in the mucosal mast cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 55
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 150 (1974), S. 213-229 
    ISSN: 1432-0878
    Schlagwort(e): Nerve cells ; Regeneration ; Neurosecretion ; Hydra viridis, littoralis ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Using whole mount preparations, nerve cells at the cut surface (head region) and also the peduncular-basal disk region were studied during various stages of regeneration (zero hour — 96 h) in Hydra. Leucomethylene blue staining technique allows excellent stainability of nerve cells and thus a statistical count of them at the specified stages of regeneration was obtained. Within 1 h after transection a significant increase (P 〈 0.001) in release of neurosecretory droplets occurs. Between 4 and 15 h of regeneration the number of perikarya remains relatively constant, but the number of processes increases by 200%. This indicates that neurons in Hydra have the capacity to regenerate their processes. Their growth in length is dramatically illustrated at 18 hrs. of regeneration. This degree of anastomosing arrangement is not observed in any other stage of regeneration. After this time the majority of processes break down releasing the neurosecretory materials. A study of the number of perikarya, the number of neurites and the number of neurosecretory droplets in regenerating animals reveals a continuous increase in the number of nerve cells and neurosecretory droplets released for up to 24 h. With the accumulation of nerve cells at the cut surface (24 h of regeneration) there is a simultaneous appearance of tentacle outpushings. The tentacles increase in number and length during the subsequent periods of regeneration. As the regenerative process approaches completion (72–96 h) the number of neurosecretory droplets released decreases, approaching the pre-transection levels as seen in normal animals. It is suggested that the neurosecretory material may act as a “trophic” agent which stimulates differentiation of interstitial cells into nerve cells and thus influences the regenerative process.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 56
    ISSN: 1432-0878
    Schlagwort(e): Milk ; Fat globule membrane ; Carbohydrates ; Chemistry ; Ruthenium red ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fat globules of the cream fractions of human and rat milk were stained with ruthenium red. Under the electron microscope, discrete granules and an amorphous coat of lesser density are seen at the surface of the milk fat globules. Since ruthenium red binds anionic groups selectively, it is probable that the granules containe the greatest concentration of these groups. The cream fraction of rat milk contains hexoses, hexosamines, methylpentoses and sialic acid. Methylpentoses and hexosamines are significantly enriched in the cream fraction. It is concluded that the finding of a surface coat in milk fat globules is in keeping with the Bargmann-Knoop model and suggests a distinct mechanism for carrying certain complex carbohydrates in milk. The role of the negative charges at the outer surface of the membrane coat in maintaining fat globules in suspension and in binding certain cations such as calcium is suggested.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 170 (1976), S. 1-16 
    ISSN: 1432-0878
    Schlagwort(e): Tissue culture cells ; Mycoplasma ; Light microscopy ; Transmission electron microscopy ; Scanning electron microscopy ; Morphometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The host-parasite relationship of HeLa M cells artificially infected with a bovine species of Mycoplasma was studied by light microscopy, transmission electron microscopy and scanning electron microscopy. The use of morphometry to quantitate some of the findings was explored. The parasites were seen in locations extracellular to the cell surface. The detection of small numbers of organisms by light microscopy was well demonstrated by use of the fluorescent antibody technique. Scanning electron microscopy proved to be an excellent method for revealing the surface details of cell-parasite morphology. Ultra-thin sections showed that the parasites are aligned mostly parallel to the plasma membrane of the host cell but separated by a gap of 10 nm. Morphometry indicated an average of 69 organisms per cell surface occupying 1.7% of the surface area. An increase of 26% in diameter of the HeLa cells, possibly as a result of infection, was observed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 160 (1975), S. 505-514 
    ISSN: 1432-0878
    Schlagwort(e): Compound eyes ; Munida irrasa (Decapod) ; Retinula ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The compound eye of Munida irrasa differs in several respects from the typical decapod eye. The proximal pigment is found only in retinula cells. The eccentric cell is extremely large and expanded to fill the interstices of the crystalline tract area; thus, a typical “clear-zone” is absent. Six retinula cells course distally to screen two sides of the crystalline cone. There are approximately 12,500 ommatidia in each compound eye. There are several similarities to the typical decapod eye. Each ommatidium is composed of a typical cornea, corneagenous cells, crystalline cone cells, crystalline cone, crystalline cone tract and eight retinula cells. Distal pigment cells are present and surround the crystalline cone. The distal processes of the retinula cells also contain pigment. The retinula cell processes penetrate the basement membrane as fascicles composed of processes from adjacent retinulae.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 59
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 171 (1976), S. 449-457 
    ISSN: 1432-0878
    Schlagwort(e): Thyroid gland ; Dwarf mice ; Stereology ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Stereological methods were used to compare thyroids of dwarf mice and of their heterozygote littermates. In the thyroid of dwarf mice unorganized cellular masses, adipous tissue and ultimobranchial cysts are abundant. Follicles are small and their distribution function is unimodal. The number of cells per follicle is considerably lowered if compared with the normal. In control mice the distribution function of thyroid follicles is bimodal. These data show that the origin of the thyroid anomaly in dwarf mice is due to a drastic diminution of cell divisions, probably resulting from the lack of growth hormone.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 60
    ISSN: 1432-0878
    Schlagwort(e): Hypothalamo-adenohypophysial region Bufo bufo (L.) ; Portal vessels ; Methyl-methacrylate casts ; Light microscopy ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The vascularization of the hypothalamo-adenohypophysial region of the toad Bufo bufo (L.) (Amphibia, Anura) was studied by means of light- and scanning electron microscopy. Special attention was given to the portal vascular system of the median eminence and the pars distalis. Course and arrangement of these vessels are described.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 164 (1975), S. 193-200 
    ISSN: 1432-0878
    Schlagwort(e): Adenohypophysis (rat) ; Mitoses ; Circadian rhythm ; Influence of fixation ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The mitotic activity in the adenohypophysis of male rats during a 24 hours' cycle has been studied at the time of the spring equinox. The animals were killed by perfusion of fixative. The mitotic activity seems to be the combination of two elements: a relatively low and nearly constant activity with two peaks of high activity. The first one takes place at 6 o'clock (local time) with an index reaching 4.25; the second one occurs at 11 o'clock (local time) and its index is 2.09. The afternoon activity is weak with an average index of 0.56 between 1 p.m. and 9 p.m. The results are analyzed, discussed and compared with other results observed in different organs.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 133 (1972), S. 367-375 
    ISSN: 1432-0878
    Schlagwort(e): Nucleolar types ; Maturing erythroblasts (frog) ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Frog erythroblasts were studied in summer animals with a very active as well as reduced erythropoiesis due to experimental hibernation, the latter being administered in order to get more information on the frequency of various nucleolar types in maturing cells. The results suggest that nucleoli with nucleolonemata are a transitional nucleolar type between compact and ringshaped nucleoli. Since micronucleoli represent final nucleolar maturation changes and compact nucleoli are present in most immature cells, the sequence of nucleolar changes based on the frequency of investigated nucleolar types is as follows: compact nucleoli→nucleoli with nucleolonemata→ringshaped nucleoli→micronucleoli. The experimental hibernation produces a shift of nucleoli to less active and “maturer” nucleolar types in all stages of the erythroblastic maturation. In addition, the experimental hibernation produces the formation of ringshaped nucleoli in the first stages of the erythroblastic maturation which in summer animals usually contain compact nucleoli and/or nucleoli with distinct nucleolonemata.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 63
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 134 (1972), S. 439-458 
    ISSN: 1432-0878
    Schlagwort(e): Limbic system ; Amygdala ; Cat-cell types ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The amygdaloid complex in the cat was studied in a series of Golgi preparations. Both the lateral and the basal nucleus are composed of the same two cell types, one of which (type P) resembles the pyramidal and the other (type S) the stellate neuron of the cortex. The cortical nucleus can be divided into three layers (I, II, and III–IV) which are made up of cells similar to those in the periamygdaloid cortex. In addition, there are sufficient differences in the organization of these layers to justify a subdivision of the cortical nucleus into lateral and medial parts. The dendrites of neurons in the medial part of the central nucleus, the medial nucleus and the anterior amygdaloid area undergo less branching and carry fewer spines than those of the type P cell. The neurons in the nucleus of the lateral olfactory tract are all of the pyramidal or modified pyramidal type. These findings are discussed in relation to those of previous investigators who employed the Nissl and Golgi methods.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 64
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 27-43 
    ISSN: 1432-0878
    Schlagwort(e): Endocrine glands ; Male sexual organs ; Reptiles ; Influence of Metopirone ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Adrenals, pituitary glands, thyroids, testes and kidneys of metopirone-treated and control male lizards were studied by light microscopy. Pituitary-interrenal axis: A great hypertrophy and hyperplasia of the interrenal cells and the pituitary corticotrophs were found in the experimental group. Pituitary-thyroid axis: Metopirone-treated animals showed a moderate hypertrophy and degranulation of pituitary thyrotrophs, and signs of uneven hyperactivity of the thyroid. Pituitary-testicular axis: By effect of metopirone, a marked regression of pituitary interstitiotrophs and a virtual disappearance of the testicular interstitial gland took place. The second portion of the kidney sexual segments appeared degranulated as in castrated animals. The pituitary folliculotrophs and the seminiferous epithelium of the testis did not show alterations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 65
    ISSN: 1432-0878
    Schlagwort(e): Mammalian-type lutropin ; Pituitary ; Immunocytochemistry ; Light microscopy ; Lepidosiren (SouthAmerican lungfish)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The presence of lutropin (LH)-like material in the pituitary gland of the South-American lungfish, Lepidosiren paradoxa, has been demonstrated by means of the unlabeled antibody-enzyme method, by use of rabbit antiovine LH as first antibody. The LH-like substance was revealed in a single PAS-positive cell type primarily located in the anterior part of the distal lobe. Dot blot tests as well as conventional liquid-phase absorption experiments indicate that the anti-ovine LH antibodies possess specificity against the oLH/gb subunit. These observations indicate that dipnoans (Lepidosiren) share a number of antigenic determinants with those of mammalian LH/gb and support the concept that mammalian LH/gb, or part of it, was established early in evolution. The exact nature and physiological function of the substance detected remains to be defined.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 148 (1974), S. 277-286 
    ISSN: 1432-0878
    Schlagwort(e): Insect visual system ; Apis mellifera ; Retina-lamina projection ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The retina-lamina projection in the visual pathway of the bee was studied by the reduced silver and Golgi techniques. Two main types of visual cell axons (R-fibres) were found: (1) at least two forms of short visual fibres terminate at two levels in the lamina; (2) the long visual fibres cross the first optic chiasma and terminate at two different levels of higher order neurons in the medulla. Six short and three long visual fibres leave each retinula in the bee's eye. Whereas two types of short visual cells can be distinguished by the arborization patterns of Golgi-stained preparations, as well as by their fibre diameters, three different types of long visual fibres can be found. In each cartridge (“neuroommatidium”) the six short visual cells closely appose three monopolar cells (L-fibres, second order neurons). Thus each axon bundle crossing the first (or intermediate) chiasma contains at least six large argyrophilic fibres (three long visual cells and three monopolar cells), and these can be seen in cross-sections of reduced silver preparations. In addition, centrifugal fibres originating in the medulla and terminating in the lamina as well as amacrine (intrinsic) cells of the lamina have been resolved by Golgi impregnation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 67
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 158 (1975), S. 89-109 
    ISSN: 1432-0878
    Schlagwort(e): Insect visual system ; Firefly lamina ; Types of neurons ; Structure ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary On the basis of Golgi preparations the neuronal elements of the lamina ganglionaris (first synaptic region of the visual system) of the firefly, Phausis splendidula L., are described. Of the set of 8 retinula fibres that originate from each ommatidium of the compound eye, at least 6 terminate in the external plexiform layer. At least one, probably two, retinula fibres per ommatidium penetrate this layer to end in the medulla, via the first optic chiasma. Five types (m1–m5) of monopolar cells can be distinguished. Only two of these, m1 and m3 have dendritic fields limited to one column of the lamina mosaic; all other monopolar cells have larger fields of up to 45μm diameter. m2 and m4 have various field spreads in different strata of the external plexiform layer. m5 has process in only one stratum of the external plexiform layer. Medulla-to-lamina cells with arborisations associated with only a single column of the lamina mosaic were not observed; medulla-to-lamina cells whose fields coincide with the various strata of the external plexiform layer were found, however. The present observations are briefly compared with those made on another beetle, Hoplia farinosa L. Comparisons with other species of insects, and the relationship between structure of the eye and structure of the lamina are also discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 68
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 171 (1976), S. 513-521 
    ISSN: 1432-0878
    Schlagwort(e): Melanin ; Sclerotin ; Insect cuticle ; Light microscopy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Black cuticles of larvae and pupae from various Lepidoptera were studied by light and electron microscopy. There are striking differences in the representation of black pigmentation, especially at the ultrastructural level. Two types may be described: 1. With the light microscope black melanin-like grana, electron-dense electron microscopically, are found in the distal parts of the exocuticle. This type is demonstrated in larvae of Celerio euphorbiae, Papilio machaon, and Phalera bucephala. 2. With the light microscope a dark homogeneous layer in the distal exocuticle can be recognized, however, electron microscopically no structures correlated with this dark pigment layer. This type of pigmentation was present in pupae of Pieris brassicae and Aglais urticae; in Pieris larvae the dark pigmented layer appeared to be limited to the epicuticle. In Celerio processes of the epidermal cells are involved in transporting precursors to the exocuticle. The conclusion was reached that black pigmentation in cuticles is based on different mechanisms as proposed by structural features. The two likely mechanisms are melanization and sclerotization.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 69
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 116 (1971), S. 119-135 
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Rat ; Sex difference ; Light microscopy ; Histometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung An 260 männlichen und weiblichen Sprague-Daweley-Ratten vom 0. Lebenstag bis zur 12. Lebenswoche wird die geschlechtsdifferente Entwicklung der Nebennierenrinde histologisch und histometrisch verfolgt. Von der 4. Lebenswoche an ist die weibliche Fasciculatazelle durch ein helles, fein-granuläres Cytoplasma ohne distinkt abgrenzbare Fettvakuolen ausgezeichnet, während beim Männchen in einem kompakten Cytoplasma zunehmend größere, deutlich begrenzte Vakuolen auftreten. Im Blindversuch gelingt aufgrund dieser Kriterien die Geschlechtsdiagnose mit großer Treffsicherheit. Nach histometrischen Untersuchungen sind die weiblichen Fasciculatakerne größer als die männlichen. Bei größerem Zellvolumen ist die Kernzahl/Flächeneinheit beim Weibchen von der Pubertät an kleiner. Die Glomerulosa und die inneren Rindenschichten zeigen keine Geschlechtsdifferenzen. Fermenthistochemisch ist eine Geschlechtsdifferenz nicht nachweisbar. Die relative Zellhypertrophie in der Fasciculata der weiblichen Nebennierenrinde ist das morphologische Äquivalent eines geschlechtsdifferenten Steroidmetabolismus bei der Ratte.
    Notizen: Summary In 260 male and female Sprague-Dawley CD rats the sex dependent development of the adrenal cortex was studied histologically and by histometric procedures. Beginning in the 4th week of life the parenchymal cells in the fasciculata of the female animals are characterized by a light, finely granular cytoplasm without distinct lipid vacuoles. In the males, however, the cells show a dense, compact cytoplasm with clearly visible vacuoles increasing in size. In a blind test the sex diagnosis can be established with great accuracy. Histometrically the nuclei in the female fasciculata cells are larger than in the males. Furthermore, caused by a larger cell volume the number of nuclei per square unit is smaller in postpuberal females. The glomerulosa and the inner parts of the cortex do not show any sex differences, nor does enzyme histochemistry. The relative cellular hypertrophy in the fasciculata of the female adrenal cortex represents the morphologic equivalent of the sexual differences in the rats steroid metabolism.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 70
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 121 (1971), S. 442-454 
    ISSN: 1432-0878
    Schlagwort(e): Visual system ; Insects ; First optic chiasma ; Fibre projection ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Each optic cartridge in the lamina of Diptera1 gives rise to a bundle of fibres composed of the prolongations of at least 11 neurons (two first order receptors, R7 and R8, five monopolar cells, L1–L5 and four “centrifugal” cells, T1, T1a, C2 and C3). The bundles project to the outer surface of the second synaptic region, the medulla. The projection patterns of the bundles means that a point for point map of the cartridge arrangement in the lamina is conferred on the medulla. The cross-over of bundles, along the horizontal axis of the eye, merely reverses the lamina map on the medulla. All eleven fibres that enter a bundle at the lamina are contained within it as far as the medulla.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 71
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 131 (1972), S. 109-140 
    ISSN: 1432-0878
    Schlagwort(e): Deuterocerebrum ; Apis mellifera ; Sensory antennal fibres ; Experimental degeneration ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Bei Bienen wurden verschieden große Abschnitte eines Fühlers oder ein ganzer Fühler in Narkose abgetrennt. Nach Überlebenszeiten von einem bis zu neun Tagen wurden der Verlauf und die räumliche Verteilung der degenerierenden, sensorischen Antennenfasern im Zentralnervensystem untersucht und der Anteil der dickfaserigen Efferenz bestimmt. Folgende Befunde wurden erhoben: 1) Die Mehrheit der Glomeruli des Lobus antennalis ist in Knäuel und Hauben gegliedert; sensorische Antennenfasern ziehen hauptsächlich von außen zu den Glomerulihauben und endigen dort. 2) Ein Wulst aus feinen Faseraufzweigungen im Lobus antennalis im Bereich des Tractus olfactorioglobularis medialis wird ebenfalls von der Antenne (vom Pedicellus?) sensorisch versorgt. 3) Der größere Teil aller sensorischen Antennenfasern endigt zwar im Lobus antennalis, der Rest zieht jedoch weiter zum Lobus dorsalis. 4) Im Lobus dorsalis befinden sich Kleinglomeruli, in denen sensorische Antennenfasern endigen; daneben durchsetzt Antennenafferenz fast den gesamten Lobus dorsalis. 5) Ein Bündel dickerer, sensorischer Antennenfasern zieht durch den Lobus dorsalis weiter zum Protocerebrum und endigt im Bereich von Ocellar-Riesenfasern. 6) Ein weiteres Bündel aus dickeren, sensorischen Antennenfasern zieht durch den Lobus dorsalis in das Unterschlundganglion; zusammen mit dünneren, sensorischen Antennenfasern wird ein Schlauch aus Antennenafferenz um den Integumentnerven herum gebildet. 7) Sensorische Antennenfasern ziehen nur im Unterschlundganglion auf die kontralaterale Seite, im wesentlichen verteilt sich die Antennenafferenz jedoch ipsilateral. 8) Die aus ungefähr 20 Motoaxonen bestehende, dickfaserige Efferenz für die Antennenmuskeln verläßt die Neuropilemkalotte des Lobus dorsalis ganz lateral; meist 6 efferente Fasern ziehen im sensorisch-motorisch gemischten Antennennerven in die Antenne. 9) Im Lobus dorsalis umspinnen sensorische Antennenfasern ganz eng motorische Antennenfasern; sehr wahrscheinlich existieren an diesen Kontaktstellen Synapsen zwischen der Antennenafferenz und der Antennenefferenz ohne zwischengeschaltete Neurone. 10) Der Nerv vom Janetschen Chordotonalorgan an der Antennenbasis zieht direkt zum Lobus dorsalis und gabelt sich dort, der eine Zweig zieht in das Protocerebrum, der andere in das Unterschlundganglion.
    Notizen: Summary In worker bees a varying number of antennal segments or whole antennae were removed. After postoperative survival times ranging from one to nine days the course and the spatial distribution of the degenerating sensory antennal fibres in the CNS were investigated; the amount of thick efferent antennal fibres was evaluated. 1) The major part of the glomeruli of the antennal lobe is organized into neuropile balls surrounded by fibre caps; sensory antennal fibres enter the caps primarily from outside to end there. 2) A worm like region consisting of fine nerve ramifications in the central neuropile of the antennal lobe next to the Tractus olfactorio-globularis medialis receives also sensory fibres from the antenna (possibly the pedicel). 3) Although the greater part of all sensory antennal nerve fibres terminates in the antennal lobe, a considerable part passes by to the dorsal lobe. 4) The dorsal lobe contains smaller glomeruli than the antennal lobe, where also sensory antennal fibres terminate; moreover sensory antennal fibres are found throughout the whole dorsal lobe. 5) A bundle of thicker sensory antennal fibres passes through the dorsal lobe to the protocerebrum to terminate next to giant fibres from the ocelli. 6) Another bundle of thicker sensory antennal fibres passes through the dorsal lobe to the subesophageal ganglion; together with thinner sensory antennal fibres it builds up a “tube” of afferent antennal fibres around the tegumentary nerve. 7) Sensory antennal fibres only in the subesophageal ganglion cross to the contralateral side; essentially their distribution is restricted to the ipsilateral side of the central nervous system. 8) There exist about 20 motor axons supplying the antennal muscles; they are the most laterally situated nerve fibres in the neuropile of the dorsal lobe; generally 6 efferent fibres together with the afferent antennal fibres constitute the mixed sensory-motor antennal nerve. 9) In the dorsal lobe sensory antennal nerve fibres end on antennal motor fibres; very probably in this region direct synaptic contacts between sensory and motor fibres without intermediate interneurons occur, thus permitting monosynaptic reflexes. 10) The nerve from Janet's antennal chordotonal organ goes directly to the dorsal lobe, where it bifurcates, one twig passing to the proto-cerebrum, the other to the subesophageal ganglion.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 72
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 136 (1973), S. 45-58 
    ISSN: 1432-0878
    Schlagwort(e): Chicken ; Bursa Fabricii ; Thymus ; Spleen ; Tonsilla caecalis ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Bursa Fabricii, Thymus, Milz und Zäkaltonsillen von 63 Hühnern im Alter von 1 Tag bis zu 1 Jahr werden histologisch untersucht, wobei das Vorkommen der als bursaabhängig geltenden Keimzentren und Plasmazellen quantitativ erfaßt wird. Beide treten in der Milz und Tonsilla caecalis erst während des Reifestadiums der Bursa in zunehmender Menge auf. Mit Beginn der Bursainvolution werden Keimzentren und pyroninophile Zellen in der Milz selten, während in den Zäkaltonsillen kaum Veränderungen auftreten. Im Thymus verschiebt sich das Verhältnis zwischen Mark- und Rindenbreite zugunsten des Marks. Bei 8 Monate alten Tieren fehlt die Rinde vollständig. Plasmazellen treten im Thymusmark während des Reifestadiums der Bursa auf und nehmen mit dem Beginn deren Involution zu. In dem Zeitraum zwischen 2 Wochen und 5 Monaten ändert sich das Verhältnis zwischen reifen und unreifen Plasmazellen beständig zugunsten der reifen Plasmazellen.
    Notizen: Summary Bursa of Fabricius, thymus, spleen and cecal tonsils were histologically examined with special reference to the number of bursa-dependent germinal centers and plasma cells in 63 chickens, 1 day to 1 year old. Both structures appear in spleen and cecal tonsils increasingly during the bursal maturity stage. At the beginning bursal involution, germinal centers and pyroninophilic cells become rare in the spleen, in contrary no changes appear in the cecal tonsils. The medulla cortex ratio of the thymus changes in favour of the medulla, in animals 8 months of age the cortex is absent. Plasma cells appear in the medulla of the thymus during the bursal maturity stage and increase in number with beginning involution. During the period of 2 weeks to 5 months the proportion between mature and immature plasma cells changes in favour of mature cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 73
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 139 (1973), S. 149-170 
    ISSN: 1432-0878
    Schlagwort(e): Suctorial disc ; Echeneis naucrates ; Sustentacular tissue ; Sense organs ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die lichtmikroskopische Untersuchung der Haftscheibe des Teleostiers Echeneis naucrates führte unter anderen zu folgenden Ergebnissen: 1. Das mehrschichtige, Schleimzellen enthaltende Epithel der Scheibe weist deutliche regionale Unterschiede auf. So ist auf der Dorsalfläche der flexiblen Randlippe eine an Schleimdrüsen besonders reiche bandförmige Zone ausgebildet. Ferner werden die Eingänge in die Taschen zwischen den Lamellen des Saugapparates und die Oberfläche der medianen Hautleiste von stark schleimbildendem Epithel umgeben bzw. bedeckt. Der Schleimstreifen der Haftscheibe wird als Einrichtung zur Abdichtung der Haftfläche gedeutet. 2. Im Drüsenfeld auf der Dorsalfläche der Randlippe liegen große Sinnesorgane vom Typus der Chemorezeptoren. Ihre Funktion besteht möglicherweise in der Prüfung der Oberfläche des Wirtes, an dem sich Echeneis festsaugt. Die Angaben von Houy (1910), wonach diese Sinnesorgane in der Wand eines Kanalsystems liegen und nicht intraepithelial, beruhen auf der Fehlinterpretation artifiziell entstandener Spalten. 3. Die interlamellären Taschen der Saugplatte werden von einem verhältnismäßig niedrigen und an Schleimzellen armen, gefältelten Epithel ausgekleidet. Es ist der Beanspruchung auf Dehnung angepaßt, die bei dem Ansaugen infolge Vertikalstellung der Lamellen der Scheibe auftritt. 4. Der ovale abgeplattete Stützgewebsstreifen innerhalb der Randlippe, dessen Gewebe von Houy (1910) nicht klassifiziert werden konnte, besteht aus hyalinzelligem Chondroidgewebe (Schaffer), das von kollagenen und elastischen Fasern, ferner von einem weitmaschigen Kapillarnetz durchsetzt wird. Zarte Septen aus Kollagenfilamenten umgeben jede einzelne Hyalinzelle. Das im Zentrum des Reifens gelegene univakuoläre Fettgewebe differenziert sich aus den Hyalinzellen des Chondroidgewebes, die ihrerseits von perichondralen Fibrozyten abstammen. Auch die innerhalb der Lamellen des Saugapparates gelegenen Knorpelformationen werden von hyalinzelligem Chondroidgewebe gebildet, das mit Fettgewebe in Zusammenhang steht. 5. Die Faserarchitektur des Randstreifens entspricht der trajektoriellen Bauweise des Hyalinknorpels.
    Notizen: Summary A light microscopical study of the suctorial disc of the teleost Echeneis naucrates revealed the following details: 1. The stratified mucous-cell bearing epithelium of the disc shows distinctive regional differences. Thus the dorsal surface of the flexible marginal lip contains a peculiar glandular zone which is particularly rich in mucous cells. Furthermore, the openings to the pockets between the lamellae of the suction apparatus and the surface of the median dermal ridge are mucus producing zones. These areas are interpreted as devices for tightening. 2. In the mucous zone of the dorsal surface of the marginal lip are large sensory organs of chemoreceptor type. Possibly their function consists in the chemical assessment of the host's surface. The statement by Houy (1910) according to which these organs are located in the wall of a canalicular system rather than intraepithelially stems from his erroneous interpretation of artifactitious clefts. 3. The interlamellar pockets of the suction disc are lined by a low folded epithelium with relatively few mucous cells. It is capable of adjusting to the stretch caused by the tilting of the disc's lamellae during suction. 4. The oval flattened ring of sustentacular tissue within the marginal lip, which Houy (1910) was unable to classify, represents a chondroid tissue consisting mainly of hyaline cells (“hyalinzelliges Chondroidgewebe, Schaffer 1930”) and traversed by collagenous and elastic fibres. It also contains a wide-meshed capillary network. Each hyaline cell is surrounded by delicate septa formed by collagenous filaments. The unilocular adipose tissue in the ring's center develops from the hyaline cells of the chondroid tissue which in turn are derived from perichondrial fibrocytes. Also the cartilaginous structures within the lamellae of the suction apparatus are formed by the same chondroid tissue that is in connection with adipose tissue. 5. The spatial arrangement of the fibres and fibrils traversing the sustentacular tissue within the marginal lip corresponds to the trajectorial pattern of hyaline cartilage.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 74
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 137 (1973), S. 313-329 
    ISSN: 1432-0878
    Schlagwort(e): Nervous system ; Limulus polyphemus ; Abdominal ganglion ; Neurons ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The morphology of the first abdominal ganglion of Limulus polyphemus (L.) was examined by reconstructions from stained serial sections. This ganglion, one of a chain of eight which form the ventral cord, is bilaterally symmetrical and shows the typical invertebrate division into two zones, cellular rind and fibrous core. The core of the ganglion comprises two major longitudinal tracts which are continuous with the connectives between the ganglia and four areas of regional neuropile which occur at the roots of the nerves developed from the ganglion. Minor tracts and neuropile are present. The rind is divided into several cell groups: U-shaped lobes around the nerve roots, a lateral lobe between the nerve roots and two cell layers along the ventral aspect. Six cell types are recognized: encapsulated unipolar cells, secretory unipolar cells (two types), encapsulated bipolar cells, “neuroglandular” bipolar cells and small non-encapsulated cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 75
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 140 (1973), S. 509-534 
    ISSN: 1432-0878
    Schlagwort(e): Genital tract ; Viviparous toad ; Cyclic variations ; Light microscopy ; Biometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé L'oviducte de Nectophrynoïdes occidentalis Angel, petit crapaud vivipare d'Afrique occidentale, peut être divisé en quatre parties: le pavillon, la trompe, l'utérus et le tronc commun utérin distal. Seul le pavillon ne varie pas au cours de l'année; il reste toujours transparent et dépourvu de cellules glandulaires. Un épithélium cilié tapisse sa lumière. La trompe est un conduit rectiligne de 7 à 10 millimètres de long qui peut être divisé en quatre segments principaux, différenciés par la constitution chimique des substances de la muqueuse. La structure de la trompe est relativement simple et comparable à celle des autres Vertébrés inférieurs. Elle apparait alternativement sous deux aspects principaux: trompe au repos et trompe active. La période de repos se poursuit pendant une bonne partie de la gestation; la reprise d'activité sécrétrice s'effectue plusieurs semaines avant la parturition et atteint son maximum dans les jours qui précèdent l'ovulation. L'utérus subit continuellement des remaniements. Tour à tour vide et gravide, il passe par trois phases essentielles: une phase de nécrose s'étendant sur les douze jours qui suivent la parturition et correspondant à l'élimination de la couche superficielle de la muqueuse; une phase de prolifération, allant du douzième jour après la mise-bas jusqu'à lóvulation suivante; caractérisée par le régénération progressive de la muqueuse à partir de la couche profonde restée en dehors des processus de nécrose; une phase de sécrétion et d'hypérémie qui dure pendant toute la gestation. La partie terminale de l'oviducte, formée par la confluence des deux conduits müllériens, subit les mêmes variations que l'utérus gestant. Son épithélium est tout-à-fait comparable à celui de l'utérus; son chorion, en revanche, est beaucoup plus dense et développé mais ne possède qu'une faible vascularisation.
    Notizen: Summary The oviduct of Nectophrynoides occidentalis Angel, a small viviparous toad of West Africa, is divided into four parts: ostium, tube, uterus and the distal common uterine segment. Only the ostium does not show seasonal variations: it always remains transparent and is devoid of glandular cells. A ciliated epithelium lines its lumen. The tube is rectilinear, about 7–10 millimeters long and may be subdivided into four principal segments, on the basis of the chemical composition of the substances of the mucosa. Its structure is relatively simple and comparable to that of other lower vertebrates. Its appearance differs according to whether it is at rest or in activity. For most of the gestation period the tube is at rest but secretory activity starts several weeks before birth. It reaches its maximum during the days immediately preceding ovulation. Unlike the tube, the uterus undergoes continuous changes, which can be pregnant, divided into three essential phases: a phase of necrosis, extending to twelve days following birth, and corresponding to the elimination of the superficial layer of the mucosa; a phase of proliferation, extending from the twelfth day after birth until the subsequent ovulation, characterized by the progressive regeneration of the mucosa, which is initiated by the deep layer which was not involved in necrosis; a phase of secretion and hyperemia which lasts during the whole period of gestation. The terminal part of the oviduct, formed by the confluence of the two Müllerian ducts, undergoes the same variations as the uterus, its epithelium being completely comparable to that of the uterus; its chorion, however, is much denser and better developed but its vascularization is less intense.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 76
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 146 (1973), S. 1-14 
    ISSN: 1432-0878
    Schlagwort(e): Ventral cord ganglia ; Limulus polyphemus ; Cell types ; Neurosecretion ; Cytochemistry ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ventral cord ganglia of the horseshoe crab, Limulus polyphemus, contains six distinct cell types: three appear to be ordinary neurons and three exhibit the staining affinities of neurosecretory cells. The presumed neurosecretory cells have been termed neurosecretory cell I (NSC I), NSC II and NSC III. NSC I cells contain a colloid-like inclusion which may occur as a single small vacuole or occupy more than one-half of the cell volume. Colloid inclusions occur with greater frequency toward the periphery, although small cells of similar staining affinity occur in cords extending to the fibrous core. The histochemical tests suggest that the cytoplasm is positive for proteins, but contains no strong acidic groups which may have been derived from S-S or S-H groups. The presence of carbohydrate is also indicated. NSC II cells exhibit distinct secretory cycles. Early in the cycle the cytoplasm becomes phloxinophilic and progresses to a distinct fuchsinophilic stage. Small homogeneous irregular inclusions are found in the axon hillock during the latter stages of the cycle. Histochemical tests suggest the presence of a carbohydrate and strong acidic groups which may have been derived from S-S or S-H groups. There are small cells present which appear to be immature neurosecretory cells. NSC III cells are characterized by a perinuclear ring of cytoplasm which is stained by chrome alum hematoxylin but not by paraldehyde fuchsin. A secretory cycle may also be present in this cell type. The three cell types presumed to be ordinary neurons exhibit no particular staining affinity for the stains or tests used in this study.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 77
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 146 (1973), S. 261-279 
    ISSN: 1432-0878
    Schlagwort(e): Skeletal muscle ; Rat, Cat ; Motor endplate ; Reinnervation ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. The formation of endplates outside the original endplate region of a muscle fibre was studied in slow and fast rat muscles. It was found that such new endplates are readily formed on the soleus muscle, whereas hardly at all in the fast extensor digitorum longus. Most new endplates appear to be morphologically normal within 2 months after nerve implantation. 2. The time course of recovery of slow and fast cat muscles was followed after crushing the sciatic nerve. It was found that the slow soleus muscle recovers more rapidly than the fast flexor hallucis longus muscle. 3. The endplates of reinnervated cat muscles are more complicated than those of the control muscles, but have nevertheless fewer nerve terminals per endplate. Reinnervated muscles are more sensitive to curare and it is suggested that this is due to a decrease in transmitter release, for it was found that less acetylcholine is released from reinnervated rat hemidiaphragms than from control ones. 4. Motor and sensory reinnervation of spindles and tendon organs was studied. At the time when motor reinnervation is almost completed the sensory endings from spindles and tendon organs are highly abnormal. Thus sensory reinnervation proceeds much more slowly than motor.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 147 (1974), S. 505-527 
    ISSN: 1432-0878
    Schlagwort(e): Cartilage ; Ageing ; Chondrocyte and matrix ; Light microscopy ; Histochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Histological, histochemical, and ultrastructural investigations have been carried out on ageing costal and tracheal cartilage of rats. The following age groups of animals have been studied: 1, 7, 14, 20, 30, 45, 75 days, 6 months, and 2 years. Ageing induces cellular changes which are represented by a reduction in the number of chondrocytes, a progressive increase in glycogen deposition, and processes of degeneration, the most frequent of which is the accumulation of lipidic material within large cytoplasmic vacuoles. Changes in the intercellular matrix become evident after 20 days in costal cartilage and after 30 days in tracheal cartilage. Chondroitin sulphate decreases while keratan sulphate, whose presence is limited to the territorial matrix, increases. Glycoproteins increase slightly in young animals and then remain constant; they decrease in the subperichondrial areas in old animals. Ultrastructurally, the matrix of cartilage of young animals contains thin collagen fibrils, most of which have no periodic banding. Roundish electron dense granules are associated with these fibrils. Irregular filaments associated with small electron-dense circular bodies are present around chondrocytes as well as within cytoplasmic vacuoles. With increasing age, and coincident with the reduction of chondroitin sulphate, the thickness of collagen fibrils increases, their period becomes evident, and the associated matrix granules decrease in number and size. Areas containing these fibrils undergo calcification, which frequently starts within roundish bodies of cellular origin. Collagen fibrils with a period of 640 Å but a highly variable thickness are often present in cartilage of adult and old rats. These fibrils seem to be due to an abnormal synthetic activity of chondrocytes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 147 (1974), S. 537-549 
    ISSN: 1432-0878
    Schlagwort(e): Insect haemocytes ; Classification ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A simplified insect haemocyte classification has been formulated by a light microscopic examination of the haemolymph of insects from fifteen Orders. Six cell types or developmental stages can be distinguished: (1) Prohaemocytes, (2) Plasmatocytes, (3) Granular Cells, (4) Spherule Cells, (5) Cystocytes, and (6) Oenocytoids. The structure and occurrence of these haemocytes are described together with the structural variations which occur in each cell type. Due to considerable overlap in structure and the presence of numerous intermediates the six cell types may represent different developmental and/or functional stages of one basic cell type. The available evidence for this unitarian hypothesis is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 80
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 149 (1974), S. 267-274 
    ISSN: 1432-0878
    Schlagwort(e): Adenohypophysis ; Teleostei ; Euryhalinity ; Eta cells ; Dilatation of capillaries ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Eta cells of the pituitary of Aphanius dispar specimens adapted to sea water are densely packed and have folded nuclei. Unfolding of the nuclei accompanied by cellular hypertrophy and hyperplasia was observed 24 hours after experimental transfer of specimens into fresh water. In specimens from natural habitats and adapted over long periods to fresh water, the nuclei are rounded and cellular hypertrophy attains maximal values. Dilatation of capillaries in the hypophysis was observed in about one third of the specimens within the first few days after transfer to fresh water. In specimens adapted either to fresh water or to sea water the capillaries were normal. Epsilon cells from seawater specimens have elongated nuclei perpendicular to the basement membrane which separates the rostral neurohypophysis from the adenohypophysis; in freshwater specimens epsilon cell nuclei are rounded.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 81
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 151 (1974), S. 343-346 
    ISSN: 1432-0878
    Schlagwort(e): Cerebellar cortex ; Rhesus monkey, cat ; Basket cell axons ; Regional differences ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the cerebellar cortex of rhesus monkey and cat differences in the arrangement of basket cell axons and dendrites are described. In the anterior lobe, basket cell axons are short, very small in number and of a small diameter. In the posterior and nodulofloccular lobe, these fibers form plexus-like accumulations within the lower third of the molecular layer. In these parts they are longer, more numerous and bigger in diameter. Finally the contribution of Lugaro cell dendrites to this fiber accumulation is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 82
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 187 (1978), S. 525-534 
    ISSN: 1432-0878
    Schlagwort(e): Salivary glands ; Insects ; Innervation ; Light microscopy ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The innervation of the salivary gland of the cockroach Nauphoeta cinerea (Olivier) has been investigated with the use of light and scanning electron microscopy. Light microscopy of methylene blue stained glands reveals the presence of a dual innervation arising from the ventral nerve cord and the stomodeal nervous system; the principal innervation is that from the ventral nerve cord which passes to the gland via the reservoir ducts. Branches of these nerves form a plexus on the acinar surface, the axons of which exhibit swelling at irregular intervals. The presence of this surface plexus and the axonal swellings was confirmed by scanning electron microscopy both in normal glands and in those in which the basal lamina had been removed by means of an HCl-collagenase digestion method. No acinar plexus was seen to be formed by branches of the stomatogastric nerve that were associated with the gland. However, other branches of this nerve were clearly connected with a complex network of multipolar neurones on the surfaces of the anterior regions of both salivary reservoirs.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 83
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 192 (1978), S. 89-96 
    ISSN: 1432-0878
    Schlagwort(e): Rat metrial gland ; Fc receptors ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Cells obtained by collagenase treatment of metrial gland tissue from rats of day 12, 13, 14 and 15 of pregnancy were examined for the presence of surface membrane receptors for immunoglobulin (Fc receptors). Using an EA rosetting technique in which sheep red blood cells (SRBC) were sensitized with a rabbit anti-SRBC immunoglobulin preparation, Fc receptors were found on a proportion of the cells. The majority of the granulated metrial gland cells were not included in the rosetting cell population, suggesting that they do not possess the type of Fc receptor detected by this method. A comparison was made between results obtained when cells were counted in suspension and those obtained from cell counts on sections of fixed material. Both methods were found to yield similar results.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 84
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 245 (1986), S. 183-188 
    ISSN: 1432-0878
    Schlagwort(e): Spleen ; Lymph nodes ; Mice ; Cyclophosphamide ; Levan ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Morphological changes in spleen and lymph nodes of C57B1 mice induced by the cytotoxic agent cyclophosphamide and the polysaccharide levan, separately and in combination were studied. In the spleen, an early decrease (phase 1) and a late increase (phase 2) in weight were found to result from all drug administrations. The hypocellularity of phase 1 was due to a depletion in the white pulp affecting mainly the B-region. Splenic weight decrease was parallel to B-cell depletion and most marked in animals exposed to cyclophosphamide with levan. The splenomegaly observed during phase 2 with all treatments was due to extramedullary hematopoiesis in the red pulp. In the lymph nodes, administration of cyclophosphamide and levan produced opposite effects on the B-cell region: cyclophosphamide eliminated the germinal centers for 8 days, but levan seemed to enhance B-cell activity. In animals given both cyclophosphamide and levan, inhibition of B-cell activity began earlier than with cyclophosphamide alone. Levan does not antagonize the suppressive effect of cyclophosphamide on the B-cell component at the early phase when the drugs are given together.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 85
    ISSN: 1432-0878
    Schlagwort(e): Immunohistochemistry ; Light microscopy ; Neuroendocrine regulation ; Neuropeptides ; Columba livia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The distribution of VIP- and TRH-immunoreactivity in neurons and processes within the hypothalamus of the pigeon was investigated with light-microscopic immunocytochemical techniques. Most of the VIP-containing neurons are concentrated in the middle and caudal parts of the hypothalamus, with the greatest concentration of perikarya occurring in the medial and lateral part of the ventromedial hypothalamic nucleus and the infundibular nucleus. These cells give rise to axons that seem to extend into the median eminence. An extensive network of VIP-immunoreactive fibers and varicosities occupy the external layer of the median eminence. The majority of TRH-containing neurons is found in the anterior hypothalamus with the greatest concentration of cells in the magnocellular preoptic, medial preoptic, suprachiasmatic and paraventricular nuclei. TRH-immunoreactive fibers and varicosities form a dense arborization in the external layer of the median eminence. Lactation seems to induce substantial changes in VIP as well as in TRH-immunostaining in the median eminence and other hypothalamic regions as compared to control, sexually active animals. Furthermore, TRH-immunoreactivity decreased in the median eminence following 60-min exposure to cold. These results suggest that VIP- and TRH-containing pathways in the pigeon hypothalamus are involved in the mediation of neuroendocrine responses.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 86
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 271 (1993), S. 47-57 
    ISSN: 1432-0878
    Schlagwort(e): Brush cells ; Cell isolation ; Stomach ; Polarity ; Light microscopy ; Electron microscopy ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The brush cells (BC) are highly polarized elements occurring in epithelia of endodermal origin. They have a preferential topographical distribution in the organs in which they reside. In the stomach of the rat, BC prevail near the transitional zone separating the forestomach from the glandular stomach. Thus, a method was developed to isolate and recover BC from this organ with the aim of investigating the changes they may undergo after dissociation. Strips of the rat stomach were severed from the very proximal border of the glandular region and incubated in Hanks' balanced salt solution containing pronase. After sedimentation of the dissociated cells (crude sediment containing all stomach epithelial cell types) two successive cell fractions were prepared on preformed Percoll gradient in an attempt to enrich BC in a defined layer. BC were recovered in a fraction at a density close to 1.03 g/ml where they represented about 2% of all cells. The isolated BC changed their form from columnar to pear-shaped; however, they maintained their structural polarity over 2 h as demonstrated by light microscopy, transmission-and scanning-electron microscopy. The fine structure of BC was always satisfactorily preserved. Maintenance of the structural polarity of isolated BC is contrary to the general rule according to which all conventional epithelial cells examined to date lose their polarity after isolation. This result is discussed in relation to morphological findings in isolated sensory cells (hair cells, photoreceptor cells) leading to the suggestion that BC are more similar to these than to conventional epithelial cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 87
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 265 (1991), S. 121-128 
    ISSN: 1432-0878
    Schlagwort(e): Autonomic ganglia ; Immune system ; Light microscopy ; Mast cells ; Neurons ; Tissue culture ; Mouse (CBA) ; Rat (Wistar, C. River)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Functional interactions between mast cells and peripheral nerves may occur at sites of association seen in vivo. To study the interactions, we developed a tissue culture model of murine sympathetic neurons co-cultured with rat basophilic leukaemia (RBL-2H3) cells (homologues of mucosal mast cells) or rat peritoneal mast cells. In co-cultures of up to 3 days, light microscopy identified neurite contacts with peritoneal mast cells or RBL-2H3 cells, but not with glial cells or fibroblasts. Electron microscopy confirmed membrane-membrane contact between neurites and RBL-2H3 cells. Time-lapse analysis of interactions between neurons and RBL-2H3 cells showed that 60–100% of the cells in a given field acquired neurite contact within 17 h. In matching control studies, there was no increase in the frequency of neurite contact with cells of the rat plasmacytoma line (YB2/0): these were not selected as targets, and contacts were broken if formed. Time-lapse records of the derivation of neurites from their path suggested a neurotropic effect of mast cells, with neurite contact ensuing when the intervening distance was less than 36±4 μm. Once formed, contacts were invariably maintained throughout the period of examination (up to 72 h), in contrast to YB2/0 or fibroblast contacts. We conclude that neurons selectively form and maintain connections with cells representative of rat connective tissue-type and mucosal mast cells in vitro. Similar interactions in vivo could promote nerve/mast cell contacts, which may allow bidirectional communication between the nervous and immune systems.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
    ISSN: 1432-0878
    Schlagwort(e): Mammalian-type prolactin ; Mammalian-type somatotropin ; Pituitary ; Immunocytochemistry ; Light microscopy ; Neoceratodus forsteri (Australian lungfish)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The aim of the present study was to define at the light-microscopic level expression of prolactin and somatotropin material in the pituitary gland of the Australian lungfish, Neoceratodus forsteri, by use of polyclonal antibodies against ovine prolactin (oPRL) and bovine somatotropin (bSTH). Substances immunologically related to mammalian oPRL as well as bSTH were detected in two morphologically different cell types in the distal lobe, corresponding to the acidophilic cells. The specificity of the antibodies was initially confirmed in a porcine tissue control system. First, our absorption studies confirm that in Neoceratodus the anti-oPRL identifies part of an oPRL-like molecule different from bSTH. Secondly, the anti-bSTH identifies both part of a bSTH-like molecule proper to bovine and Neoceratodus STH, and part of a bSTH-like molecule having antigenic determinants in common with both bSTH and oPRL. This part of the oPRL is, however, not shared with the Neoceratodus PRL as revealed by the anti-oPRL. Altogether these observations support the concepts: (1) that mammalian PRL and STH, or part of those, were established early in evolution, and (2) that dipnoans as living sarcopterygians have an ancestor in common with the early amphibians. The exact nature and physiological functions of the substances detected remain to be defined.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 89
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 235 (1984), S. 51-58 
    ISSN: 1432-0878
    Schlagwort(e): Parathyroid glands ; Electron microscopy ; Light microscopy ; Quantitative histology ; Mongolian gerbil
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Stereology and semi-automatic image analysis were used with the aim of comparing the structure of parathyroid glands from untreated adult Mongolian gerbils fixed by immersion with those fixed by perfusion. Subclassification of the chief cells based upon the staining affinity or electron density of the cytoplasm was readily performed only in glands fixed by immersion, and so-called atrophic cells were observed only in these glands. The atrophic cells were often surrounded by “light” chief cells. In glands fixed by perfusion, “light” chief cells were only rarely encountered. A significant difference between glands fixed by immersion and those fixed by perfusion was found only with regard to the form of cells and nuclei, those fixed by perfusion being more spherical. When comparing individual cells within glands fixed by immersion, “light” chief cells were more spherical and had a significantly larger nuclear and cellular size, and a lower mitochondrial volume density than the “intermediate”/“dark” chief cells. Otherwise there were no significant differences in any of the parameters investigated. These data indicate that occurrence of socalled “light” chief cells and atrophic cells is a result of improper fixation. The results of this study do not favour the concept of a functional cycle with a simultaneous occurrence of active and inactive cells within parathyroid glands.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 90
    ISSN: 1432-0878
    Schlagwort(e): Key words: Thyro-parathyroidectomy ; Parathyroidectomy ; Enamel formation ; Light microscopy ; Electron microscopy ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The effects of thyro-parathyroidectomy, parathyroidectomy or thyroidectomy upon enamel formation in the rat incisor were studied. One control group and four groups of surgically treated rats were used: parathyroid autotransplanted, thyroidectomized, parathyroidectomized, and thyro-parathyroidectomized. One month after surgery, the incisors were processed for light and electron microscopy. The present study revealed perturbations of the Tomes’ process morphology, of the rod pattern in the inner enamel formation, of the enamel surface, and of the mineralization after thyro-parathyroidectomy. After parathyroidectomy, only mineralization defects could be visualised. No effects were observed in enamel after thyroidectomy. A severe hypocalcemic state as seen in thyro-parathyroidectomized rats affects the enamel shape, and mineralization, and the morphology and function of secretory ameloblasts. Knowledge of the way in which the alteration of the enamel surface is produced should contribute to a better understanding of the development of tooth enamel.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 91
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 203 (1979), S. 181-188 
    ISSN: 1432-0878
    Schlagwort(e): Ventral prostate ; Epithelial cells ; Electron microscopy ; Light microscopy ; Older rats
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ventral prostatic secretory epithelial cells in older rats were studied by light and electron microscopy. The cells vary in height in different parts of the same organ, and ultrastructurally they show the presence of a developed secretory apparatus such as well-developed Golgi body and abundant rough endoplasmic reticulum. They also show signs of a depressed secretory activity, involving occasional emiocytosis of apical secretory vacuoles and a paucity of condensing vacuoles in the Golgi region and above it. Further, they are characterized by the frequent occurrence of supra and paranuclear pleomorphic lysosomes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 210 (1980), S. 501-515 
    ISSN: 1432-0878
    Schlagwort(e): Mechanoreceptors ; Eye ; Dolphins ; Whales ; Irido-corned angle ; Light microscopy ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A study of the structure and distribution of encapsulated corpuscles (corpuscles of Rochon-Duvigneaud) in the irido-corneal (anterior chamber) angle in 42 adult eyes from nine species of odontocete cetaceans representing each of the five families in this group indicates a diversity of form and function. The corpuscles occur as single features or multiple groupings with each species having a distinct pattern. No definite phylogenic or environmental patterns were seen although sometimes there were similarities among related genera. The neural structure of the angle suggests that these receptors probably respond to a variety of stimuli including intraocular pressure, vitreous displacements, external muscular force applied to the sclera and cornea, and changes in the volume of the massive iris/choroid vascular system.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 276 (1994), S. 295-307 
    ISSN: 1432-0878
    Schlagwort(e): GABAA receptors ; Light microscopy ; Electron microscopy ; α1 subunit ; β2/3 subunit ; γ2 subunit ; Immunocytochemistry ; Rabbit (New Zealand)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The distribution of gamma-aminobutyric acidA (GABAA) receptors in the rabbit retina is investigated and compared with the distribution of GABAergic neurons using immunocytochemical methods. Antibodies against the α1, β2/3, and γ2 subunits of the GABAA receptor label subpopulations of bipolar, amacrine and ganglion cells. Double labeling experiments show that the γ2 subunit is colocalized with the α1 and the β2/3 subunits in bipolar, amacrine and ganglion cells. Electron microscopy reveals that in the outer plexiform layer, GABAA receptor immunoreactivity is present on dendrites of cone bipolar cells adjacent to the cone pedicles. Bipolar cell dendrites are also receptor-positive at synapses from interplexiform cells. Some receptor immunoreactivity is found intracellularly in processes of horizontal cells. In the inner plexiform layer, GABAA receptor immunoreactivity is present on both rod bipolar and cone bipolar axon terminals at putative GABAergic input sites. Amacrine and ganglion cell processes in sublamina a and b are also labeled.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 176 (1993), S. 43-52 
    ISSN: 1615-6102
    Schlagwort(e): Hyphal tip growth ; Spitzenkörper ; Cytoskeleton ; Cryofixation ; Freeze substitution ; Transmission electron microscopy ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Light and transmission electron microscopy were used to examine hyphal tip cells of the fungusAllomyces macrogynus (Chytridiomycetes). A well defined apical body, i.e., Spitzenkörper, was observed at the extreme apex of hyphal cells. This distinctive, spherical cytoplasmic region consisted of a granular matrix devoid of ribosomes and most organelles. To our knowledge this is the first report describing such a structure in hyphae of an aseptate fungus. Vesicles (45–65 nm diameter) were concentrated in the peripheral cytoplasm of the apex, while relatively few were observed within the Spitzenkörper. Filasomes, spherical patches of dense fibrillar material containing a microvesicle core, were abundant in the apical regions near the plasma membrane. Microtubules traversed the Spitzenkörper at various angles and were in close association with the plasma membrane. Microfilaments were observed as individual elements in the cytoplasm or were organized into bundles. Individual microfilaments were frequently in close association with the plasma membrane, vesicles and microtubules. In the immediate subapical region mitochondria, multivesicular bodies, microbodies, Golgi equivalents and nuclei were abundant.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 108 (1981), S. 361-367 
    ISSN: 1615-6102
    Schlagwort(e): Echinostelium ; Slime mold ; Light microscopy ; Mitosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Light microscopical observations on mitosis in living material of the amoebal and plasmodial phases of the MyxomyceteEchinostelium minutum de Bary (orderEchinosteliales) are reported for the first time. The uninucleate amoebal cell undergoes centric, open spindle mitosis whereas the multinucleate plasmodium exhibits acentric, closed spindle mitosis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 153 (1989), S. 14-23 
    ISSN: 1615-6102
    Schlagwort(e): Pedinomonas tuberculata ; Monomastix spec ; Pseudopedinella elastica ; Flagellar developmental cycle ; Light microscopy ; Uniflagellated algae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Flagellar development during cell division was studied by light microscopy in three taxa of uniflagellated algae,Pedinomonas tuberculata (Chlorophyta),Monomastix spec. (Chlorophyta), andPseudopedinella elastica (Chromophyta). As shown by electron microscopy during interphaseM. spec, andP. elastica contain a mature, non-functional second basal body, andP. tuberculata contains an immature (i.e., shorter) non-functional second basal body. Two different types of flagellar development were observed in the three taxa: inP. tuberculata the parental flagellum is transferred to one of the progeny cells, whereas the other progeny cell receives a newly formed flagellum that grows from the second non-functional basal body. InM. spec. andP. elastica the parental flagellum is either completely retracted (P. elastica) or partially retracted and autotomized (M. spec); each dividing cell develops two new flagella (from two newly formed basal bodies) which are distributed to the two progeny cells. The uniflagellated condition in algae can thus be attained by two completely different mechanisms: a non-functional second basal body is either the younger (no. 2; inP. tuberculata and otherChlorophyta) or the older (no. 1; inP. elastica and presumably otherChromophyta) of the two basal bodies.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    ISSN: 1615-6102
    Schlagwort(e): Cyanophora paradoxa ; Glaucocystophyceae ; Flagellar developmental cycle ; Light microscopy ; Basal body numbering
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Flagellar development during cell division was studied inCyanophora paradoxa using agarose-embedded cells, Nomarski optics and electronic flash photography. The cells bear two heterodynamic and differently oriented (anterior and posterior) flagella. Prior to cell division, cells produce two new anterior flagella while the parental anterior flagellum transforms into a posterior flagellum. The parental posterior flagellum remains a posterior flagellum throughout this and subsequent cell divisions. The development of a single flagellum thus extends through at least two cell cycles and flagellar heterogeneity is achieved by semiconservative distribution of the flagella during cell division. Based on these principles a universal numbering system for basal bodies and flagella of eukaryotic cells is proposed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    ISSN: 1573-739X
    Schlagwort(e): Antimalarials ; Artemisia annua L ; Artemisinin ; Biosynthesis ; Chemistry ; Clinical trials ; Pharmacology ; Phytochemistry ; Sesquiterpenes ; Toxicology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Artemisinin, a sesquiterpene lactone endoperoxide isolated fromArtemisia annua L., and a number of its semisynthetic derivatives have shown to possess antimalarial properties. They are all eflective againstPlasmodium parasites that are resistant to the newest and commonly used antimalarial drugs. This article gives a survey of the literature dealing with artemisinin-relaled antimalarial issues that have appeared from the end of 1989 up to the beginning of 1994. A broad range of medical and pharmaceutical disciplines is covered, including phytochemical aspects like the selection of high-producing plants, analytical procedures, and plant biotechnology. Furthermore, the organic synthesis of artemisinin derivatives is discussed, as well as their mechanism of action and antimalarial activity, metabolism and pharmacokinetics, clinical studies, sideeffects and toxicology, and biological activities other than antimalarial activity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Springer
    Pharmacy world & science 10 (1988), S. 93-95 
    ISSN: 1573-739X
    Schlagwort(e): Anthracyclines ; Chemistry ; Drug stability ; Mitomycins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Pharmacy world & science 10 (1988), S. 101-116 
    ISSN: 1573-739X
    Schlagwort(e): Chemistry ; Chromatography ; Etoposide ; Immunoassay ; Metabolism ; Podophyllotoxin ; Pharmacokinetics ; Teniposide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Etoposide (VP 16-213) and teniposide (VM 26) are semisynthetic epipodophyllotoxin derivatives active against a variety of tumours. The clinical efficacy has led to an increasing interest in these compounds. This review presents information on the mechanism of action, biochemical pharmacology, bioanalysis, metabolism and pharmacokinetics of etoposide and teniposide.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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