ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Bücher
  • Artikel  (279)
  • Forschungsdaten
  • Electron microscopy  (279)
  • Springer  (279)
  • Macmillan Magazines Ltd.
  • Oxford University Press
  • 2010-2014
  • 2005-2009
  • 1995-1999  (39)
  • 1980-1984  (70)
  • 1975-1979  (170)
  • 1935-1939
  • 1925-1929
  • 2012
  • 1997  (6)
  • 1995  (33)
  • 1984  (16)
  • 1982  (22)
  • 1981  (32)
  • 1979  (43)
  • 1978  (59)
  • 1977  (68)
  • 1938
  • 1928
  • Medizin  (278)
  • Chemie und Pharmazie  (1)
Sammlung
  • Bücher
  • Artikel  (279)
  • Forschungsdaten
Verlag/Herausgeber
  • Springer  (279)
  • Macmillan Magazines Ltd.
  • Oxford University Press
Erscheinungszeitraum
  • 2010-2014
  • 2005-2009
  • 1995-1999  (39)
  • 1980-1984  (70)
  • 1975-1979  (170)
  • +
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Lasers in medical science 10 (1995), S. 93-104 
    ISSN: 1435-604X
    Schlagwort(e): Copper vapour laser ; Electron microscopy ; Illumination time ; Numerical modelling ; Optimal treatment ; Port-wine stain
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract This paper reports the electron microscopy results obtained from two patients who were treated with 5 W of yellow (578 nm) light from a copper vapour laser with an illumination time of 3.6 ms and a 0.3 mm spot diameter. The endpoint of treatment was transient blanching. Following treatment, erythema was observed. There was minimal damage to the epidermis and non-vascular tissue such as the nerve fibres. There was severe damage to the endothelial cells of the ectatic vessels. Twenty-four hours after treatment, platelet activation and collagen were present, indicating that these vessels were no longer viable. Theoretical calculations are used to determine the flow of heat within and away from a 50μm diameter vessel. From this, heating of the entire vessel is shown to occur with illumination times of 4 ms, with minimal heating of the non-vascular tissue. Shorter illuminations do not heat the entire vessel, while the use of longer illumination times will cause excessive damage to the surrounding non-vascular tissue. Illumination times close to 4 ms must be regarded as optimal.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 260 (1982), S. 564-569 
    ISSN: 1435-1536
    Schlagwort(e): lin. Polyethylene ; Single crystals ; Heat of Fusion ; DSC ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Recently published results for solution crystallized PE single crystals have shown, that the experimental heat of fusionΔH * is higher, if the solvent is exchanged to silicon oil (oil suspension samples) as compared with dried mats. This has been interpreted by the collapse of the original hollow pyramids during drying, inducing lateral defects within the lamellae. The present investigation does not confirm this unexpected result.ΔH * of dried mats (T c 66 to 91 °C) and of the corresponding oil suspension samples agree within the rather small limits of experimental error. The crystallinities as derived fromΔH *, density or WAXS are in excellent agreement. SEM micrographs of cold fractured dried mats show their spongy macromorphology, but TEM micrographs of stained ultra-thin sections reveal the lamellar morphology of the walls, consisting of curved lamellae and stacked hollow pyramides. If a dried mat is sintered at room temperature, a dense transparent film is obtained with a rather regular stacked morphology of large flat lamellae.ΔH * of these films agrees with that of the original mat.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 25 (1978), S. 217-222 
    ISSN: 1432-0827
    Schlagwort(e): Bone mineral ; Electron microscopy ; X-ray diffraction ; Dark field
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Electron microscopical observations of the size and shape of bone mineral crystallites have not been in complete agreement with X-ray diffraction findings. The two prevalent viewpoints consider bone mineral crystals to be either rod, or plate like in habit. There appears to be agreement that the smallest dimension of the crystals is about 5 nm, but there is discrepancy in the reported c-axial lengths. The method of dark field imaging is used to obtain a quantitative measurement of the c-axial length distribution in rabbit, ox and human bone: mean c-axial lengths 32.6 nm, 36.2 nm and 32.4 nm, respectively, show no significant difference at the 5% level to the mean c-axial length measured by X-ray line broadening. Both bright and dark field images strongly suggest that bone mineral has a plate like form. Reasons for past discrepancies are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    ISSN: 1432-0827
    Schlagwort(e): Parathyroid hormone ; Osteoclasts ; Electron microscopy ; Morphometry ; Metaphysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The effects of parathyroid hormone (PTH) on the size of the osteoclasts, nuclei, ruffled borders, and clear zones in long bones of thyroparathyroidectomized (TPTX) rats were quantitated as a function of time. These data were compared with the number of osteoclasts in the bone and with plasma calcium levels. A significant increase in the average size of the ruffled borders was demonstrated 30 min after injection of 50 U of purified bovine PTH, and of the clear zones 30–90 min after PTH. This was followed at 90 min by an increase in the average size of the cells. The sizes of ruffled borders and clear zones dropped sharply to control levels after 6 h, whereas the size of the cells remained elevated up to 12 h and returned to control values at 24 h. Plasma calcium levels were increased, but not significantly, between 30 min and 6 h. An increase in the number of osteoclasts was significant after 12 h. Removal of the parathyroid glands did not diminish the normal activity of osteoclasts. In animals with intact glands injection of 50 U of PTH did not cause a significant change in cell size or resorbing apparatus. It is concluded that PTH acts to rapidly stimulate the bone resorptive activity of osteoclasts and to cause a delayed increase in their number.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 181 (1997), S. 425-437 
    ISSN: 1432-1351
    Schlagwort(e): Key words Olfactory receptor cells ; Olfactory bulbectomy ; Olfactory axotomy ; Electrophysiology ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract This study investigated whether contact with the olfactory bulb was necessary for developing and renewing olfactory receptor neurons (ORNs) to attain normal odorant responsiveness, and whether the anatomical and functional recoveries of the olfactory epithelium were similar in both bulbectomized (BE) and bilaterally axotomized (AX) preparations. In vivo electrophysiological recordings were obtained in response to amino acids, a bile acid [taurolithocholic acid sulfate(TLCS)] and a pheromonal odorant [17α, 20β,-dihydroxy-4-pregnen-3-one (17,20P)] from sexually immature goldfish. Both transmission and scanning electron microscopy indicated that the olfactory epithelium degenerated in BE and AX goldfish. Within 1–2 weeks subsequent to the respective surgeries, responses to high concentrations (〉0.1 mmol · l−1) of the more stimulatory amino acids remained, whereas responses were no longer obtainable to TLCS and 17,20P. At 4 weeks, responses to amino acid stimuli recovered to control levels, while responses to TLCS and 17,20P were minimal. By 7 weeks post bilateral axotomy, the olfactory epithelium recovered to a condition similar to control sensory epithelium; however, the rate of degeneration and proliferation of receptor neurons in BE preparations appeared to remain in balance, thus blocking further recovery of the olfactory epithelium. At 7 weeks post surgery, odorant responses of AX and BE goldfish to TLCS and 17,20P were still recovering.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Mycopathologia 60 (1977), S. 175-177 
    ISSN: 1573-0832
    Schlagwort(e): Aspergillus fumigatus ; Spore formation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Mycopathologia 61 (1977), S. 117-119 
    ISSN: 1573-0832
    Schlagwort(e): Prototheca ; Colorless alga ; Plastids ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract An ultrastructural investigation of six different species of Prototheca showed that all of them contained starch grains enclosed in double-membrane-bounded structures recognized as plastids. It is concluded that these unicellular species of Prototheca must be considered as non-photosynthetic algae.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 33 (1981), S. 143-151 
    ISSN: 1432-0827
    Schlagwort(e): Calcium transport ; Cytochalasin B ; Dihydrocytochalasin B ; Colchicine ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary In vivo calcium absorption was studied in normal and rachitic chicks. Cytochalasin B (CB) at a concentration of 25 µg/ml added to the medium inside the duodenal lumen inhibited calcium absorption (20 min) from 82.5±1.9% of calcium absorbed in the controls to 59.2±3% in normal and from 70.0±2.3% to 47.0±2.1% in rachitic chicks. In vitro studies by everted ileal sacs of young rabbits also showed an inhibition of active transport of calcium due to CB. Whereas in the controls the ratio of45Ca concentrations in serosal and mucosal media (60 min) was 7.2±0.32, the ratios were 5.24±0.52; 4.40±0.36; 3.40±0.42; 5.77±0.52; 1.38±0.08; and 1.06±0.02 in the presence of CB at concentrations of 5, 10 and 25 µg/ml; colchicine 10−4M, Na citrate 0.02M, and heat-devitalized conditions, respectively.45Ca concentration in the mucosal scrapings was also affected. It showed an increase from controls (15,101±404 cpm/mg) and correlated with CB concentration: 17,378±489, 19,015±1000, and 20,201±362 at 5, 10, and 25 µg/ml, respectively. Dihydrocytochalasin B also inhibited active calcium transport and caused an increase in45Ca concentration in the mucosal scrapings. Correlated electron microscopic studies showed certain changes in the brush border, especially in some actin microfilaments in the terminal web region. It seems that these morphological alterations may be related to transcytoplasmic movement of calcium.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 33 (1981), S. 381-384 
    ISSN: 1432-0827
    Schlagwort(e): Alcohol ; Electron microscopy ; Growth plate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary We have previously demonstrated that ethanol has a direct toxic effect on the rat skeleton characterized by decreased trabecular bone volume. In the present study, we examined the ultrastructure of the distal radial epiphyseal growth plates in these same animals. Eight weeks of ethanol administration to 12 male rats results in serum alcohol levels of 140 mg/dl but did not alter the width or light microscopic appearance of the radial growth plate. Quantitative electron microscopy failed to demonstrate morphologic evidence of toxicity in the skeletal cells. We conclude that although ethanol appears to have a direct effect on rat bone characterized by enhanced resorption, toxicity is not attended by ultrastructural changes in the skeletal cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 33 (1981), S. 529-540 
    ISSN: 1432-0827
    Schlagwort(e): Bone cells ; Electron microscopy ; PTH ; PGE1
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Four different cell populations—designated PF, OB, OC, and PC—were isolated from calvaria of 18-day-old chick embryos for analysis of the effects of hormones on bone tissue. The cell populations were studied with histological and biochemical methods. Apart from the well-known cell types present in calvaria, a new cell type was found in the noncalcified organic matrix between the osteoblastic layer and the calcified matrix. These cells were provisionally called osteocytic osteoblasts. They represent the “transition state” between osteoblasts and osteocytes. On the basis of histological studies with light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), the PF population was considered to originate primarily from the periosteal fibroblasts, the OB population from the osteoblasts and osteocytic osteoblasts. The population of cells still present in calvaria after removal of periosteal fibroblasts and osteoblasts was called the OC population. This cell population was very much enriched with osteocytes. The fourth isolated population (PC) was a mixed population of fibroblasts, osteoblasts, and preosteoblasts. On exposure to parathyroid hormone (PTH), all four cell populations showed increased lactate production, but only the OB and OC populations displayed increased cAMP production. Prostaglandin E1 (PGE1) stimulated cAMP production in both OB and PF cells. From the results of this study it was concluded that PTH receptors are present on all of the cell types studied, but that occupancy of the receptor induces adenylate cyclase stimulation only in osteocytes and fully differentiated osteoblasts.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 26 (1978), S. 181-190 
    ISSN: 1432-0827
    Schlagwort(e): Cellular calcium ; Electron microscopy ; Osteoblasts ; Chondrocytes ; Mineralization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The calcium distribution in cartilage and bone cells during beginning ossification of fetal mouse long bones was studied after fixation with 2% K-pyroantimonate in 1% osmium. In the developing periosteum, the future osteoblasts showed a sparse cation-antimonate precipitate over the cytoplasm. In young osteoblasts the precipitate was accumulated on the mitochondrial membranes and the plasmalemma. Both organelles were sharply outlined by precipitate in the mature osteoblasts at the onset of mineralization. X-Ray microprobe analysis of these organelles demonstrated the presence of both Sb and Ca. In the extracellular compartment, a collagen-associated precipitate with 50 to 60 nm periodicity appeared during osteoblastic differentiation. During the initial phase of matrix mineralization, a random gross precipitate appeared in the matrix and seemed to be accumulated by osmiophilic matrix vesicles while the collagen fibrils lost their precipitate. Subsequently, during the confluent phase of matrix mineralization, the precipitate rapidly disappeared from the cells, leaving them devoid of precipitate once they were surrounded by mineralized matrix. Similar changes were found in the chondrocytes of the growth plate, but cartilage collagen, unlike osteoid collagen, did not bind precipitate. The results indicate that both osteoblasts and calcifying cartilage cells bind calcium prior to matrix mineralization. Bone collagen has strong pyroantimonate binding capacity, but it is not directly involved with initial stages of matrix mineralization, which starts in close association with matrix vesicles.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 23 (1977), S. 215-223 
    ISSN: 1432-0827
    Schlagwort(e): Amorphous mineral ; Bone ; Electron microscopy ; Ultracryotomy ; Ultramicro-incineration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The fine structure of the extracellular phase of avian medullary bone and embryonic chick femur was examined in thin sections prepared by ultracryotomy and ultramicroincineration. Since contact with solutions was completely avoided, little or no loss or dislocation of mineral constituents could occur. Amorphous bone mineral (ABM) was present in two forms: as 15–30 nm spheres and as a structure-free haze. Removal of all organic material by low temperature ashing left the ABM intact. Crystals were usually associated with the ABM. In newly ossifying regions clusters or nodules of randomly oriented crystals and ABM appeared to coalesce when they reached approximately 1 μm in diameter. In highly calcified regions crystals appeared to be oriented along collagen fibers. ABM did not appear to be associated with collagen. Unmineralized collagen was visible in osteoid after staining with dry OsO4 vapor and it appeared to be diverted around nodules. Structures which resembled matrix vesicles were present. Selected area electron diffraction patterns indicated the presence of hydroxyapatite.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 13
    ISSN: 1432-0827
    Schlagwort(e): Bone sialoprotein ; osteoblast ; Bone matrix ; Electron microscopy ; Immunolocalization ; noncollagenous protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract Bone sialoprotein was immunolocalized at the EM level in thin Lowicryl K4M sections of rat bone. Because of the unconventional EM morphology of the bone matrix seen in thin demineralized acrylate sections, the pattern of immunolabeling was compared with detailed structural images of demineralized bone obtained using an en bloc treatment of tissue samples with the cationic electron ‘dye’, Malachite Green (MG), which provides stabilization and retention of anionic material throughout specimen processing. A system of structures corresponding to the sites of bone sialoprotein (BSP) immunoreactivity, as seen in Lowicryl K4M thin sections, could be readily identified in the MG-treated, expoxy thin sections. This system includes the cement lines, and aggregates of similar material within mineralized bone and mineralizing osteoid. The virtual identity of BSP distribution with the arrangement of the MG-visualized material indicates that a BSP-enriched, noncollagenous phase can be demonstrated using different, unrelated tissue preparation and imaging protocols for EM. Besides improving our understanding of the distribution of bone sialoprotein in bone, these data assign a previously unrecognized structural dimension to noncollagenous material in the bone matrix.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 25 (1978), S. 179-190 
    ISSN: 1432-0827
    Schlagwort(e): Decalcification ; Electron microscopy ; Calcified matrices
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The ultrastructure of calcifying cartilage and bone has been examined under the electron microscope after using three different methods of decalcification. The first was carried out before embedding (by soaking specimens in EDTA or formic acid), the second after embedding (by floating ultrathin sections on formic acid), and the third after embedding (by soaking embedded specimens in EDTA or formic acid), and with later re-embedding. The first procedure invariably induces drastic changes in the fine structure of the cells and calcified matrix, probably as a results of the extraction of organic material along with extraction of mineral. The second and third procedures make it possible to preserve ultrastructural details perfectly in both cells and calcified matrix. Of the two, the third procedure is preferable because of its greater simplicity. In areas that are still calcifying, these post-embedding decalcification techniques reveal the presence of crystal-associated, filamentous organic structures which are not recognizable in specimens decalcified before embedding. These structures, which could have a key role in inducing and regulating crystal formation and growth, are less evident in fully calcified areas (but not at their borders). This may partly be due to the loss of glycan components in the matrix during calcification. The most important determinant, however, seems to be the fact that during calcification the components of the matrix, including collagen fibrils, are involved in an aggregation process which reduces the amounts of free chemical groups available for reaction with the stain solution. Because post-embedding decalcification does not disturb this state of aggregation, the stainability of the matrix and the electron microscopic evidence of its components remain very low.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 24 (1977), S. 191-197 
    ISSN: 1432-0827
    Schlagwort(e): Amelogenesis imperfecta ; Hypocalcification ; Hypoplasia ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary An ultrastructural study of teeth with amelogenesis imperfecta revelaed various aspects of microcavities in the enamel surface, which ranged from isolated imprints of ameloblasts corresponding to the mildest lesions at the end of amelogenesis, to pits caused by the death of 20 to 30 ameloblasts at the beginning of amelogenesis. Abnormalities in the shape of the prisms can be observed. Further, crystals are distributed randomly within a prism or at the junction of 2 contiguous prisms while intercrystalline spaces are widened, indicating in various places the lack of a preferred orientation of the crystals. In amelogenesis imperfecta, two different crystalline periods are found: 1 of about 250 Å, the other of about 500 Å and over. The fact that amorphous areas are found among the crystals of enamel may be related to different stages of crystallization. However, it was not possible to find any lattice defect.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 24 (1977), S. 239-242 
    ISSN: 1432-0827
    Schlagwort(e): Cementum ; Lysis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Examination of microradiographs from the deciduous teeth of pigs revealed large lacunae or radiolucent zones close to the cemento-dentinal junction. Electron microscopic studies of the ground sections showed areas or irregularly shaped zones devoid of mineral and filled with collagen fibers. In the wide unmineralized zones, spherical clusters of crystallites were noted. Several cementum lacunae bordered by a broad rim of unmineralized collagen fibers were noted and some lacunae also contained zones of a moderately electron dense material. This material did not yield a diffraction pattern, while the mineralized part of the cementum gave the diffraction pattern typical of hydroxyapatite.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 25 (1978), S. 45-51 
    ISSN: 1432-0827
    Schlagwort(e): CaCO3 ; Amino acids ; Sheaths ; Ligament ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The aragonite crystals in the molluscan bivalve hinge ligament are surrounded by an organic sheath which is distinct from the remainder of the ligament matrix. Methods have been developed to isolate these sheathed crystals from the ligaments ofSpisula solidissima andMercenaria mercenaria employing a papain digestion of the matrix protein. The sheathed crystals fromSpisula have a CaCO3/protein ratio of 11.1 and those fromMercenaria a ratio of 29.6. The sheathed crystals and the empty crystal sheaths have been examined by electron microscopy for structural integrity. The sheath proteins exhibit much smaller proportions of the amino acids glycine and methionine than the hinge ligaments. These are characteristic amino acids of high concentration in the hinge ligaments of both species. The concentrations of acidic and basic amino acids are increased about two fold in the sheaths over those of the ligaments. Otherwise there is little similarity in the amino acid composition of the sheaths in the two species. However, SDS electrophoresis shows the sheaths of both to contain a major protein component with a molecular weight of about 25,000. The sheath protein from theMercenaria ligament contains about 5% carbohydrate and that ofSpisula sheaths less than 1% carbohydrate.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 29 (1979), S. 101-105 
    ISSN: 1432-0827
    Schlagwort(e): Osteon ; X-ray diffraction ; Pole figures ; Electron microscopy ; Calcification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The X-ray diffraction method based on pole figures has been applied to single osteon samples in order to obtain information about the texture of the inorganic bone fraction and the way it changes during calcification. The osteon samples were cylindrically shaped, with axes corresponding to those of the haversian canals. Selection was carried out according to the degree of calcification and the orientation of collagen bundles and inorganic particles. Osteons at both the initial and final stages of calcification were chosen. Arrangements of fiber bundles and inorganic particles in successive lamellae characteristic of three types of osteons were selected: longitudinal, alternate, and transversal. The results indicate that in all three types of osteons, the long axis of the sample is apparently the only direction of orientation because the transversally oriented crystallites give an isotropic diffuse scattering as would be expected if all the inorganic particles were irregularly oriented around the osteon axis. The number of longitudinally oriented crystallites increases progressively from transversally oriented osteons to alternately and longitudinally oriented ones. The crystallite orientation in an axial direction increases in fully calcified osteons. This last result is in agreement with the electron microscopic finding that the long needle-shaped crystallites covering much more than a major collagen period and measuring 40–45 Å in width increase in number as calcification proceeds.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 56 (1995), S. 566-570 
    ISSN: 1432-0827
    Schlagwort(e): Cathepsin inhibitors ; Osteoclasts ; Resorption ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract This study was designed to evaluate the effects of specific and potent cathepsin inhibitors on osteoclastic resorptive functions in vitro by means of a novel ultrastructural assay system. Mouse bone marrow cell-derived osteoclasts were suspended on dentine slices and cultured for 48 hours in the presence of either E-64 (a generalized cysteine proteinase inhibitor) or Z-Phe-Phe-CHN2 (a selective cathepsin L inhibitor). After the removal of cultured osteoclasts, co-cultured dentine slices were examined using electron microscopy: backscattered (BSEM), scanning (SEM), and atomic force (AFM). In morphometric analyses of BSEM images, there were no significant differences in the areas of demineralized dentine surfaces between control and inhibitor-treated groups, suggesting that cathepsin inhibitors had no effect on dentine demineralization by cultured osteoclasts. However, in SEM and AFM observations, both inhibitors remarkably reduced to the same extent, the formation of deep resorption lacunae on dentine slices that had resulted from degradation of matrix collagen. In addition, Z-Phe-Phe-CHN2 treatment produced deeper, ring-like grooves with little collagen exposure in shallow resorption lacunae. These results strongly suggest that (1) cathepsins released by osteoclasts are involved in the formation of deep resorption lacunae, and (2) cathepsin L plays a key role in bone resorption.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 33 (1981), S. 119-124 
    ISSN: 1432-0827
    Schlagwort(e): Avian eggshell ; Microstructure ; Electron microscopy ; Electron diffraction ; Calcite growth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The eggshell of the domestic fowl has been studied by transmission electron microscopy and diffraction. Thin sections of shell were prepared by chemical and ion-beam thinning techniques. Each calcite column of the palisade layer consisted of crystallites of diameter 20 to 30 µm with some tendency for crystallite alignment within a single column. Evidence indicates that there was no significant preferred orientation in the palisade layer as a whole. Only in the surface layer was any preferred orientation detected, and here {1014} planes tended to lie parallel to the surface. The results are compared with previously published data, and calcite nucleation and growth are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 25 (1978), S. 133-143 
    ISSN: 1432-0827
    Schlagwort(e): Osteon ; X-Ray diffraction ; Electron microscopy ; Calcification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary To obtain information on the changes in the inorganic bone fraction during calcification, low- and wide-angle X-ray diffraction techniques and electron microscopy have been applied to single osteon samples. The samples were cylindrically shaped and their axes corresponded to the axes of the Haversian canals. The selection was made according to the degree of calcification and the orientation of collagen bundles and inorganic particles. Osteons at both the initial and final stages of calcification were chosen. Arrangements of fiber bundles and inorganic particles in successive lamellae characteristic of three types of osteon were selected, that is, longitudinally structured osteons, transversely structured osteons, and alternately structured osteons. The results indicate that in osteonic lamellar bone there are two types of inorganic particles: (1) granules arranged in linear or needle-shaped entities with maximum width 40–45 Å, which are regularly distributed at the level of the main band of the collagen fibrils where their maximum length reaches the length of the main band itself; that is, about 400 Å; and (2) very long crystallites, with a diameter of 40–45 Å, which grow with their crystallographicc-axis parallel to the collagen fibrils and cover much more than a major collagen period.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 200 (1979), S. 15-27 
    ISSN: 1432-0878
    Schlagwort(e): Lymph vessels ; Testis ; Man ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The distribution of lymph vessels in the human testis was investigated using ink injection methods, and light and electron microscopy. Lymph capillaries occur in the septula testis but are absent in the intertubular tissue. They consist of endothelial cells provided with an incomplete basal lamina and anchoring filaments of the adjacent connective tissue. Frequently, the endothelial cells are separated by gaps measuring up to 2μm. The lymph capillaries of the septula testis are connected to lymph vessels in the rete testis and tunica albuginea. These vessels have occasional smooth muscle cells and valves. At the posterior margin of the testis, the network of lymph vessels merges into collecting ducts, which together with vessels derived from the rete testis are drained by the lymphatic system in the spermatic cord.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 200 (1979), S. 329-334 
    ISSN: 1432-0878
    Schlagwort(e): Median eminence ; Axon terminals ; Tanycytes ; Electron microscopy ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The present ultrastructural study proves the existence of nerve terminals closely apposed to the plasmalemmata of tanycytes in the rat median eminence. Several of these “axo-tanycytic” endings display remarkable accumulations of agranular endoplasmic reticulum in the form of pleomorphic vesicles which are closely apposed on either side of the plasma membrane of each cell compartment. Some of these vesicular profiles give the impression of structural continuity across both membrane systems. This phenomenon is discussed in the context of being a potential substratum for communication between both cell compartments.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 176 (1977), S. 23-36 
    ISSN: 1432-0878
    Schlagwort(e): Lateral line organ ; Shark (Mustelus manazo) ; Neuromasts ; Cell types ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The lateral line organ of the spotted shark is characterized by its semi-cylindrical shape. Each organ (neuromast) is so closely apposed to the next that the individual neuromasts are almost continuous. The neuromast is composed of receptor cells, supporting cells and mantle cells. The receptor cells bear one kinocilium and up to 40 stereocilia. Bi-directional arrangement of the receptor cells as occurs in teleosts was demonstrated. Afferent and efferent nerve endings were found at the base of the receptor cells. The supporting cells extend from the basal lamina to the free surface. Long microvilli and a cilium-like “ciliary rod” project from the top of each supporting cell. The cell contains relatively few elements of the Golgi apparatus and little rough endoplasmic reticulum, but mitochondria and filaments are abundant. The mantle cell limits the lateral margin of the neuromast. It is distinguished from the supporting cell because of its long crescent-shaped nucleus and scarce, short microvilli. Myelinated nerve fibres are found in the subepithelial connective tissue but not in the epithelium. The fine structure of the shark lateral line organ suggests that this organ is in an intermediated step of evolution between that of lamprey and teleost.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 176 (1977), S. 191-203 
    ISSN: 1432-0878
    Schlagwort(e): OsO4 ; Cholesterol ; Symbiotes ; Aphids ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Pea aphids left for 48 h in unbuffered osmium tetroxide show heavy staining of many organelles in the symbiote-containing cells (mycetocytes and sheath), embryos and oenocytes very similar to that characteristic of mammalian sterol-synthesizing cells. However, the staining of the pea-aphid cells is, to a large extent, dependent on the presence of cholesterol benzoate, or free cholesterol, in the aphid's diet. In aphids cultured in vitro with 3H mevalonate in the presence of added cholesterol, the incorporation of label into the cholesterol and lanosterol fractions is significantly reduced. If the dietary cholesterol effects a similar inhibition in vivo, the cholesterol-dependent osmium staining could be due to precursors(s) of cholesterol accumulating in the intracellular sites described. There is also osmium staining of large (normally electron-transparent) vacuoles in mycetocytes, gut and fat body, irrespective of dietary cholesterol.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 176 (1977), S. 417-429 
    ISSN: 1432-0878
    Schlagwort(e): Fat body ; Galleria mellonella ; Basement membrane ; Ruthenium red staining ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fat body lobes of Galleria mellonella are surrounded by basement membrane — a fine granular layer of connective tissue. This membrane has an affinity for ruthenium red. The results obtained after treatment of the fat body with neuraminidase, hyaluronidase, phospholipase C and proteolytic enzymes suggest that glycoproteins and phospholipoproteins are constituents of this basement membrane. The basement membrane also has the ability to bind concanavalin A-peroxidase, which is associated with the presence of mannoside residues.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 27
    ISSN: 1432-0878
    Schlagwort(e): Skeletal muscle ; Protamine ; Endocytosis ; Autophagic vacuolation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The uptake in vitro of horseradish peroxidase (HRP) in mouse skeletal muscle was examined by electron microscopy and chemical determination. In muscles exposed to an HRP solution for 60 min at +37°C, HRP infiltrated the basal lamina of muscle fibres and caused an intense labelling of their sarcolemma. In addition HRP was found within the transverse tubules. Exposure to HRP for 30 min at +37°C followed by HRP together with a polycationic protein (protamine) for 30 min at +37°C caused an intracellular vesicular uptake of HRP. Intracellular HRP was found in numerous vesicles, membrane limited bodies and vacuoles. Protamine also induced focal autophagic vacuolation with progressive muscle fibre degeneration. An intracellular HRP uptake or muscle cell vacuolation could not be detected in the absence of protamine or when the incubation temperature was + 4°C. Chemical determination of HRP uptake was in general agreement with the morphological results. The uptake of HRP in the presence of protamine was stimulated at +31°C and blocked at +4°C. The results suggest that in skeletal muscle in vitro intracellular uptake of macromolecules occurs by endocytosis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 177 (1977), S. 81-85 
    ISSN: 1432-0878
    Schlagwort(e): Electron dense plaques ; Pancreatic islets ; Parathyroids ; Electron microscopy ; Calcium binding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Small electron dense plaques (EDP) were found in the plasma membrane of pancreatic islet A-, B- and D-cells and parathyroid chief cells of mice and gerbils. The identification of the EDP was facilitated by the use of special fixation techniques. The EDP may represent sites of calcium binding in the cell membranes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 177 (1977), S. 127-140 
    ISSN: 1432-0878
    Schlagwort(e): Microtubules ; Retina ; Electron microscopy ; Rainbow trout
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the retina of the rainbow trout (Salmo gairdneri, Richardson) two types of microtubular structures are demonstrated. Besides the normal type of microtubules (about 200 Å in diameter), occurring in all cell types of the retina, a second type is described which is termed microtubule-like structure (MLS) because of its extracellular localization. These MLS have a diameter of about 250 Å under the same preparative conditions in which the normal microtubules appear 180–200 Å thick. The interspace between the tubules is smaller than between the microtubules. Specific MLS to membrane associations exist, which are analyzed by serial sectioning and tilting procedures. It is suggested that the MLS have their origin at small membranous extrusions of the plasmalemma. These extrusions could contain nucleation sites for the MLS-formation within the extracellular space. It remains unknown which cell type produces the MLS proteins and which factors are responsible for the aggregation of the subunits to intact MLS.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 177 (1977), S. 221-226 
    ISSN: 1432-0878
    Schlagwort(e): Actin-like filaments ; Myoid cell ; Testis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Microfilaments in the myoid cells of the peritubular tissue in the mouse, swine and human testis bind heavy meromyosin (HMM) and form arrowhead complexes. The periodicity of the arrowhead complexes is about 35 nm. Individual filaments show arrowheads that point in the same direction. Opposing polarity of the HMM-bound filaments is also observed. The microfilaments do not bind HMM in the presence of 10 mM ATP. After treatment with the contraction medium of Hoffmann-Berling, the filaments appear to be undulated. These observations indicate that the microfilaments in the myoid cell are actin-like in nature. A small number of thicker filaments (about 10 nm in diameter) which do not bind HMM is also observed in the cell. Microfibrils which have been reported around the human myoid cell are also found in the swine.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 200 (1979), S. 337-344 
    ISSN: 1432-0878
    Schlagwort(e): Glomerulo-tubular feedback ; Tight junctions ; Macula densa ; Distal tubule ; Electron microscopy ; Freeze fracture ; Horseradish peroxidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the present study the tight junctions at the macula densa were compared to those of the adjacent straight and convoluted segments of the distal tubule using freeze fracturing and thin sectioning techniques. Only insignificant differences were found in the number of strands and the apico-basal depth of the tight junctions in the three distal tubular segments of rat, dog and tree shrew. In experiments with horseradish peroxidase on mice and tree shrews, the tracer did not penetrate the apical junctions in any of the distal tubular segments. Our findings do not support the concept of considerably higher permeability of the tight junctions at the macula densa, as previously reported. Gap junctions were never observed in the distal nephron. The present results suggest that the glomerulo-tubular feedback is more likely to be mediated by transcellular resorption of solutes than by passive diffusion through a leaky paracellular shunt pathway.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 32
    ISSN: 1432-0878
    Schlagwort(e): T-lymphocytes ; Blast cells ; Lymph node ; Electron microscopy ; Stereology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Changes in the volumes and surfaces of subcellular compartments of unstimulated small lymphocytes and immunoblasts in mouse axillary lymph nodes have been established using stereological techniques. Blast transformation was induced in vivo with dinitrochlorobenzene (DNCB). Cell samples were obtained by random sampling regimes applied at light and electron microscopic levels. From electron micrographs the volume densities of euchromatin, heterochromatin, nucleoli, mitochondria, Golgi apparatus and rough endoplasmic reticulum were determined. Cell surface/volume ratios were also computed. By estimating mean nuclear volumes using light microscopy, it was possible to calculate absolute compartmental volumes and to evaluate the plasma membrane surface areas of average cells. Transformation in this model was characterized by a considerable cellular hypertrophy and a substantial increase in plasmalemma surface. Hypertrophy was the consequence of increases in the volumes of all measured intracellular compartments, notably euchromatin and “residual cytoplasm” (including ground cytoplasm and free ribosomes). These changes are discussed in the context of the altered metabolic status of cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 33
    ISSN: 1432-0878
    Schlagwort(e): Optic neuropile ; Crustacea ; Catecholamine ; Fluorescence histochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The crustacean optic neuropiles, the lamina ganglionaris and especially the medulla externa, show a specific pattern of green fluorescence with the fluorescence histochemical method of Falck-Hillarp. Normally, only the terminals and the cell bodies fluoresce, but in reserpine-treated animals exogenous catecholamines are taken up by the whole adrenergic neuron and are thus visualized as a whole. Incubating crayfish optic neuropiles in dopamine or α-methylnoradrenaline after reserpine treatment demonstrated a tangential neuron connecting the lamina and the medulla externa. The morphology of this tangential neuron differs from the two types of tangential neurons, Tan1 and Tan2, previously characterized with Golgi techniques. The catecholaminergic neuron thus constitutes a third tangential neuron type.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 182 (1977), S. 401-407 
    ISSN: 1432-0878
    Schlagwort(e): Microtubules ; Sciatic nerve (rat) ; Tannic acid ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Tannic acid in glutaraldehyde was used to stain microtubules in myelinated and unmyelinated axons of rat sciatic nerve. In the majority of areas the tannic acid failed to penetrate the unmyelinated axons whilst penetrating neighbouring myelinated axons, suggesting a difference in the ability of the two types of nerves to exclude tannic acid. Where tannic acid had penetrated the unmyelinated axons the 13 protofilament substructure and size of the microtubules appeared identical to those seen in the myelinated axons.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 35
    ISSN: 1432-0878
    Schlagwort(e): Albinism ; Pigment epithelium ; Tyrosinase ; Electron microscopy ; Carassius auratus L.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ultrastructural studies, and cytochemical and biochemical determinations of tyrosinase activity were conducted on the pigment epithelium of albino and xanthic goldfish eyes. In eyes of xanthic goldfish, two types of melanosomes are present, spherical and elongated. Melanized melanosomes are absent in the eyes of the albino goldfish, but elongated lamellar premelanosomes are observed. Internal vesicles are present in both melanosome types in the pigment epithelium of the xanthic goldfish but are absent in premelanosomes of the albino. There are also differences in the distribution of lipid droplets, smooth endoplasmic reticulum and Golgi complexes with the latter two being more abundant in the albino. Tyrosinase was not identified cytochemically; however, the enzyme was demonstrated biochemically in the pigment epithelia of both albino and xanthic goldfish. The enzyme is associated with the particulate and soluble fractions of both types of eyes. Particulate albino tyrosinase may be solubilized by triton X-100 treatment. Tyrosinase inhibitors are present in the particulate fractions of both albino and xanthic goldfish eyes. Thus, in the goldfish, ocular albinism appears to be a multiple defect at the molecular and ultrastructural levels.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 176 (1977), S. 407-416 
    ISSN: 1432-0878
    Schlagwort(e): Chick embryo ; Electron microscopy ; Glial differentiation ; Neuron differentiation ; Reaggregation cultures
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Dissociation and reaggregation cultures from different portions of the chick embryo neural tube were made, and the resulting aggregates were fixed for electron microscopy after 1, 5, 8, 14, 16 and 22 days in vitro. All cultures (pure aggregates of telencephalon, optic lobe or neural retina, and combined aggregates made from mixtures of optic lobe plus neural retina or optic lobe plus telencephalon) show a common timing of neuronal and glial morphological differentiation. During the first week in vitro, some cells developed neuronal characteristics in the absence of morphological evidence of glial differentiation. Numerous axonic processes usually formed fascicles with all the fibers running parallel to each other. Axonic growth cones were abundant and a few immature synapses were also present. The second week in culture was characterized by the disappearance of growth cones and the increase in number and morphological maturation of synapses. Morphologically detectable glial differentiation began by the end of this week, and during the third week almost every neuronal element, including the axonic fascicles, became associated with glial cells showing astrocytic features.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 37
    ISSN: 1432-0878
    Schlagwort(e): Gastric mucous cells ; Differentiation ; 3H-thymidine incorporation ; Histochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Gastric surface mucous cells (SMC), mucous neck cells (MNC) and their undifferentiated and immature precursors were studied by light and electron microscopic histochemistry. The secretory granules of SMC were smaller, more electron dense and more reactive to PAS and its analogues than those of MNC. Alcian blue demonstrated that the mucus of SMC was acidic and that of MNC was neutral. The periodic acid —thiocarbohydrazide —silver proteinate method revealed the presence of carbohydrates in the Golgi apparatus, condensing vacuoles, secretory granules, apical vesicles and tubules and cell coat. Maturation of SMC during their migration towards the free surface was reflected by an increase in size and number of secretory granules, an increase of RER and microfilaments, and a decrease of microvilli and apical vesicles and tubules. The secretory granules of older SMC were less acidic and possessed a proteinaceous core. Most MNC were fully differentiated, but some immature MNC containing only a few granules were found. Furthermore, undifferentiated cells and intermediates between SMC and MNC were also observed. The presence of both transitional and intermediate forms indicates that both SMC and MNC arise from the same population of undifferentiated cells. Incorporation of 3H-thymidine revealed that undifferentiated cells, isthmic SMC, MNC and intermediate cells are proliferative. No proliferative activity was found in foveolar SMC, parietal, chief, fibrillovesicular or endocrine cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 177 (1977), S. 159-180 
    ISSN: 1432-0878
    Schlagwort(e): Muscle transplantation ; Rat ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Rat soleus muscles were autografted from right to left legs, and regeneration following necrosis of all original myofibres was studied after 7 to 250 days. The best regenerates were from grafts replacing all calf muscles and sutured to the tendon stumps. After 30 days the size of such regenerates was equal to those from minced gastrocnemius muscles: the cross sectional area of muscle tissue was 30% (1.7 mm2) and the number of fibres was 180% (4500) of normal soleus muscles; the fibre diameters were 10 to 40 μm. To increase the number of myoblasts before grafting some muscles were injured by Ringer solution of 70° C and transplanted after 2 days. Nevertheless, this did not influence regeneration. After 7 days clusters of myotubes occurred in the periphery of the muscle. These myotubes originated from myoblasts growing like endothelial cells on the inner face of the persisting basal lamina tubes of necrotic fibres. After 30 days the muscles were vascularized. Fibres formed in a common basal lamina detached and so looked “split”. Satellite cells of new fibres came from undifferentiated cells associated with myotubes, i.e. from myoblasts. After 30 days and more regenerates contained three sorts of fibres. 1. Thin (5 to 20 μm) fibres resembling fetal muscle fibres. They were most prominent after 30 days, and probably not yet innervated. 2. Thin (10 μm) degenerating fibres as in long-time denervated muscles. 3. Thick (more than 30 μm) mature looking fibres which were innervated and revealed end-plates. Half of the grafts studied after 30 and 60 days contained unmyelinated and myelinated axons which had grown along strands of surviving Schwann cells. After 250 days, only two muscles were studied which both lacked innervation. Almost all regenerates contained muscle spindles, which, however, were not innervated. Within the persisting spindle capsules new muscle fibres had been formed from satellite cells of the former intrafusal fibres.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 177 (1977), S. 247-268 
    ISSN: 1432-0878
    Schlagwort(e): Adrenal medulla ; In vitro ; Phase contrast microscopy ; Catecholamine histochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Explants and enzyme-dispersed cells of adrenal medulla from 10–12 day old rats were studied in culture for up to 3 weeks. Adrenomedullary chromaffin cells, nerve cells and satellite cells were clearly discernible. The nerve cells were few in number and did not show catecholaminespecific fluorescence. Chromaffin cells stored catecholamines, as judged by the Falck and Hillarp method, in varying amounts decreasing with age of the cultures and the distance from the explants. Exocytosis profiles observed with the electron microscope suggested that cultured chromaffin cells also released catecholamines. Moreover, the cells formed processes and frequently migrated into the outgrowth. After 6 days in culture, the great majority of chromaffin cells stored noradrenaline as revealed by electron microscopy with few adrenaline-storing cells being visible. Granular vesicles (∼ 80–240 nm in diameter) with cores of different electron densities were occasionally present in the same cell suggesting the occurrence of mixtures of primary and secondary amines. Apart from “chromaffin” granules, small clear and densecored vesicles (∼ 40–60 nm) were found both in the somata and cell processes. Chromaffin cells and their processes were often closely apposed and occasionally formed specialized attachment zones. As a whole, chromaffin cells in culture resembled small granule-containing cells in sympathetic ganglia. 0.5 mM dbcAMP prevented dedifferentiation of chromaffin cells as judged by the lack of processes, the size and amount of “chromaffin” granules and the high number of adrenaline-storing cells present after 6 days in culture. NGF caused a striking increase in the number of axons growing out from expiants.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 177 (1977), S. 291-305 
    ISSN: 1432-0878
    Schlagwort(e): Juxtaglomerular apparatus ; Tupaia ; Gap junctions ; Renin ; Freeze-fracturing ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The vascular pole of the juxtaglomerular apparatus in Tupaia belangeri was studied with special reference to the intercellular contacts of the periendothelial cells and the endothelium of the vas afferens. The periendothelial cells of the vascular pole of the glomerulum are connected by numerous gap junctions; and the granulated epithelial cells are suggested to form a functional unit. Probably there is a continuity of this system troughout the entire vascular pole including (1) all granulated cells, (2) all lacis cells, (3) the mesangium cells and (4) the adjacent smooth muscle cells of the vas afferens and vas efferens. Analysis of the endothelial junctions shows a zonular arrangement of tight junctions indicating a rather tight blood-tissue barrier next to the glomerular vascular pole. The ultrastructure of the different cell types of the vas afferens is also described, emphasizing the granulated epithelial cells and their innervation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 41
    ISSN: 1432-0878
    Schlagwort(e): Gut epithelium ; Ciona intestinalis, Mytilus edulis ; Endocrinecells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ultrastructural evidence has been found for the presence of polypeptide hormone-producing cells in the gut of Ciona intestinalis L. and Mytilus edulis L. which do not appear to have been described before. Due to their localization and ultrastructural characteristics, it is suggested that the cells in Mytilus edulis probably produce an insulin-like substance and that some of these cells in Ciona intestinalis may produce 5-HT (5-Hydroxytryptamine). In each species only one granulated cell type can be observed. The granules, which are electron dense and membrane bound, also show a halo. The average diameter of the granules is 100–200 nm for Ciona and 200–400 nm for Mytilus.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 177 (1977), S. 539-553 
    ISSN: 1432-0878
    Schlagwort(e): Sensory receptors ; Peripatopsis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Three types of sensilla occurring on the lips and on the antennae of Peripatopsis moseleyi have been investigated by scanning and transmission electron microscopy. On the lips sensory spines can be found which contain numerous cilia originating from bipolar receptor cells. They reach the tip of the spine where the cuticle is modified. The perikarya of the sensory cells, a large supporting cell with a complicated surface and a second type of receptor, form a bud-like structure and are surrounded by a layer of collagen fibrils. The second receptor cell bears apical stereocilia as well as a kinocilium which are directed towards the centre of the animal — thus the cell appears to be turned upside down. The sensilla of the antennae are 1) sensory bristles containing two or three kinds of receptor cells, one of which bears an apical cilium and one kind of supportive cell and 2) sensory bulbs located within furrows consisting of receptor cells with branched cilia and two kinds of supportive cells which are covered by a modified thin cuticle. According to the electron microscopical findings the sensory spines on the lips are presumably chemoreceptors. The sensory bristles on the antennae can be regarded as mechanoreceptors and the sensory bulbs as chemoreceptors.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 178 (1977), S. 155-167 
    ISSN: 1432-0878
    Schlagwort(e): Electromotor system ; Oval nucleus ; Synapses, junctions ; Electron microscopy ; Torpedo marmorata
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The morphology of the oval nucleus of neonatal Torpedo marmorata is described at the light and electron microscopic level of examination. The nucleus is unique relative to other central electromotor centers of electric fish so far described being bilaterally symmetrical, composed of two nerve cell types, and possessing no gap junctions between neurons and their processes. This particular structural plan presents difficulties in accounting for presumed synchronous discharge since it has been strongly argued that electrotonic coupling by means of gap junctions is the primary process by which synchronization is accomplished. Close membrane apposition and dendritic bundling, common features within the nucleus, are discussed as possible alternative structural correlates.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 200 (1979), S. 435-442 
    ISSN: 1432-0878
    Schlagwort(e): Fat body ; Calliphora ; Electron microscopy ; Cytochemistry ; Ecdysterone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the larval fat body of Calliphora erythrocephala, protein accumulation and autophagic activity occur prior to the onset of puparium formation. The involvement of the lysosomal system in the degradation of sequestered protein and cell organelles can be demonstrated by the electron microscopical cytochemical localization of the lysosomal marker enzyme acid phosphatase in so-called protein granules. These granules contain not only newly synthetized or absorbed protein but also remnants of cell organelles such as mitochondria and endoplasmic reticulum. Ligation of the larvae behind the brain-ring gland complex prevents the appearance of these acid phosphatase positive granules. They can be induced in ligated larvae by the injection of 20 hydroxyecdysone into the abdomen. These findings are briefly discussed in relation to the role of moulting hormones in normal development, especially with regard to the induction of autophagic activity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 45
    ISSN: 1432-0878
    Schlagwort(e): Lipid absorption ; Pyloric caeca ; Electron microscopy ; Feeding experiment ; Rainbow trout
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Rainbow trout were killed 4 and 18 h after being fed wax ester-rich marine Zooplankton and the absorptive epithelium of the pyloric caeca examined by electron microscopy. Numerous osmiophilic drops were seen in the lamina propria underlying the epithelium of fish killed at both times, but these drops were only abundant within columnar epithelial cells of fish killed 4 h after feeding. Pinocytotic profiles were not common at the luminal plasma membranes, nor were osmiophilic droplets seen in the terminal web area between the luminal plasma membrane and the extensive smooth endoplasmic reticulum. Numerous osmiophilic droplets, 30–100 nm in diameter, were present in the cisternae of the smooth endoplasmic reticulum with up to five separate droplets per individual cisterna. Columnar epithelial cells also contained up to 100 large osmiophilic drops (“conglomerates”) which tended to be concentrated in the supranuclear (Golgi) regions. The conglomerates were 250–1200 nm in diameter and were themselves made up of smaller droplets 30–400 nm in diameter. Conglomerates were present both within intracellular membranes and free in the cytoplasm. Osmiophilic droplets in the intercellular spaces and lamina propria were similar in size to individual droplets within conglomerates. We conclude that triacylglycerols are elaborated in the smooth endoplasmic reticulum, transferred to and processed in the Golgi region and finally discharged serosally as chylomicron-like particles of not greater than 400 nm diameter.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 182 (1977), S. 1-16 
    ISSN: 1432-0878
    Schlagwort(e): Epithalamus (Rat) ; Supraependymal nerves ; Electron microscopy ; Circumventricular organs ; Medial habenular nucleus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Transmission and scanning electron microscopy of the rat epithalamus shows a regional variation in the distribution of Supraependymal nerves (SN) which correlates well with Supraependymal yellow fluorescence reported by Richards et al. (1974). The medial habenular nucleus, the intercommissural and suprahabenular recesses, the habenular commissure and the fibrae periventriculares thalami have the greatest density of SN/100 μm of ependymal surface. The floor of the suprahabenular and intercommissural recesses is covered by non-ciliated ependyma. The significance of these findings is discussed with respect to (1) a direct functional relationship of SN with ependyma, and (2) a possible participation of the non-ciliated ependyma of the suprahabenular and intercommissural recesses in secretory activity whereby the CSF serves as a vehicle for neuroendocrine communication.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 182 (1977), S. 73-79 
    ISSN: 1432-0878
    Schlagwort(e): Ovary ; Oocyte elimination ; Peritoneal epithelium ; Primordial follicle ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Numerous ovarian oocytes of primordial follicles are lost postnatally by their elimination into the peritoneal cavity during days 1–6 in young mice. It is rarely found in animals over 2 weeks old. This phenomenon has been investigated by light and EM techniques. Oocytes that become extruded from the ovary this way appear to pass between the cells of the covering epithelium. The ultrastructural changes that take place during this process are described.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 176 (1977), S. 251-263 
    ISSN: 1432-0878
    Schlagwort(e): Gastrin cells ; Electron microscopy ; Fixation ; Granule maturation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructural appearance of gastrin cell (G cell) granules was studied after different fixation procedures. When the pH of prefixation was varied there was greater preservation of the electron density of granule cores after acidic (pH 5.0 and 6.0) than after neutral or alkaline (pH 7.0 and 8.0) prefixation. Increasing duration of prefixation at pH 7.3 resulted in progressive loss of electron density of the granule core with swelling and occasional rupture of the limiting membrane. In tissues where most granules had been rendered electron lucent by fixation, those granules remaining dense cored were preferentially located close to the Golgi zone. These findings indicate that the electron density of G cell granules is profoundly affected by conditions of fixation, and that immature granules are more resistant to loss of core density than mature granules. They also suggest that the gastrin granule in vivo, like other polypeptide granules, may have a “solid”, osmotically inactive core.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 176 (1977), S. 275-284 
    ISSN: 1432-0878
    Schlagwort(e): Neural lamella (wax moth) ; Ruthenium red ; Enzyme digestion ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The outer surface of the neural lamella, the connective tissue ensheathing the brain, shows the ability to bind ruthenium red in the wax moth larva. Ruthenium red-positive material is sensitive to neuraminidase, hyaluronidase and to some extent to phospholipase C, what suggests that the negative charge on the external surface of the neural lamella depends on the presence of the anionic groups of sialic and hyaluronic acids and phospholipids.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 198 (1979), S. 477-486 
    ISSN: 1432-0878
    Schlagwort(e): Embryonic heart ; Myogenesis ; Sarcomere ; Crustacea (Homarus americanus) ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Cardiomyoblasts in the myocardium of embryonic lobsters at 3–4 weeks and 6 months of development were examined with the transmission electron microscope in order to describe the events in the formation of sarcomeres in a neurogenic cardiac system. Thick and thin myofilaments appear first in the cell periphery near the sarcolemma. They align in parallel in a sequential fashion to form consecutive sarcomeric units. Well-defined A and I bands appear before any semblance of a Z line is present. The initial sarcomere is anchored to the sarcolemma by the insertion of thin myofilaments into a region of electron dense material associated intimately with the sarcolemma. Myofibrils grow outward in several planes away from the electron-dense regions of membrane that serve as focal points for myofibril formation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 198 (1979), S. 521-526 
    ISSN: 1432-0878
    Schlagwort(e): Adenohypophysis ; Electron microscopy ; L-DOPA ; Lysosomes ; Chinese quail, Excalfactoria chinensis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Intraperitoneally injected L-DOPA was found to stimulate strongly the lysosomal system of all of the cell types of the adenohypophysis. We suggest that this amine may play a role in the regulation of the secretory activity of the gland by mediating the lysosomal activity, this role being of variable importance according to the fluctuations in hormonal activity. Ultrastructural changes occur in some cell types following injection of L-DOPA. The question as to whether these changes are induced directly by L-DOPA or via the monoaminergic system of the hypothalamus and its hypophysiotropic hormones is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 199 (1979), S. 509-517 
    ISSN: 1432-0878
    Schlagwort(e): Olfactory bulb ; Giant cells ; Neurosecretion ; Electron microscopy ; Labyrinth fish
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The giant cells in the olfactory bulb of labyrinth fish, most likely belonging to the nervus terminalis, show ultrastructural features of active synthesis of secretory material. Dense core vesicles (70–100 nm in diameter), found in the perikaryon as well as in the axon, are the possible storage sites of the secretory substance. Its chemical nature is unknown. In some of these vesicles acid phosphatase is demonstrable. Large membrane-bound bodies (up to 2000 nm in diameter), either containing an electron dense matrix or debris of cytoplasmic organelles, are also acid phosphatase-positive, suggesting their lysosomal nature. Some other ultrastructural characteristics of these cells are also described.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 237 (1984), S. 219-226 
    ISSN: 1432-0878
    Schlagwort(e): Spermatogonia ; Spermatocytes ; Carbohydrates ; Guppy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The structure of guppy (Poecilia reticulata) spermatogonia and spermatocytes has been studied using electron microscopy. The spermatogonia, situated at the apex of the seminiferous tubule, are almost all surrounded by a network of Sertoli cells; they have very diffuse chromatin and one or two large nucleoli. The cytoplasm contains relatively few organelles, although annulate lamellae are found. The mitochondria have few cristae and are concentrated at one pole of the cell; they are sometimes found with intermitochondrial cement. These spermatogonia are separated from each other, having no intercellular bridges or inclusion in Sertoli cells, and are relatively undifferentiated; they correspond to stem cells. The spermatogonia beneath the apex are organized into cysts. First-generation spermatogonia are more dense and heterogeneous, their nuclei becoming smaller and their chromatin becoming denser during successive generations. In spermatocytes, the synaptinemal complex exists as a modified form until metaphase. The concentration of organelles in the cytoplasm increases and the organelles become more diversified as spermatogenesis progresses. Many cytoplasmic bridges are observed (several per cell), indicating that the cells remain in contact after several divisions. These changes in germ cell structure have been related to some of the characteristic features of spermatogenesis in guppy, e.g. the large number of spermatogonial generations and the complexity of spermiogenesis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 201 (1979), S. 159-163 
    ISSN: 1432-0878
    Schlagwort(e): Insulin secretion ; Acid-base changes ; Electron microscopy ; Pancreas perfusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructural changes in pancreatic β cells were studied following glucose-induced insulin secretion in vitro, at two different extracellular pH (7.4 and 7.8). The pancreata perfused at pH 7.4 exhibited a biphasic insulin response to glucose challenge together with signs of increased emiocytotic activity and numerous microtubules in the β cells. Conversely, the pancreata perfused at pH 7.8 showed a significant decrease in insulin secretion, and their β cells revealed scarce emiocytotic images and a marked increase of intracellular granulolysis. These results represent the ultrastructural correlate of the reduced insulin secretion produced by metabolic alkalosis in the perfused rat pancreas.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 55
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Steroid release ; Rabbit ; Electron microscopy ; Morphometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of the rabbit adrenal cortex was investigated. The parenchymal cells display the ultrastructural features of steroid-producing cells, and also contain numerous electron-dense bodies frequently located near intercellular canaliculi, which open into the subendothelial space. Short-term ACTH-administration induced a noticeable decrease in the volume of the lipid compartment in the cells of all three cortical zones and a significant increase in the volume of dense bodies in the cells of zona fasciculata and zona reticularis. The hypothesis that these dense bodies are secretory granules is discussed in the light of biochemical evidence showing that ACTH increases the concentration of both corticosterone and cortisol in the decapsulated-enucleated adrenal homogenate and does not affect the activity of two lysosome-marker enzymes (i.e., acid phosphatase and β-glucuronidase).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 56
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 186 (1978), S. 121-133 
    ISSN: 1432-0878
    Schlagwort(e): Proximal tubule ; Tight junctions ; Ultrastructure ; Electron microscopy ; Freeze fracturing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The morphology of tight junctions of the renal proximal tubule was studied comparing the pars convoluta and pars recta of rat, golden hamster, rabbit, cat, dog and tupaia. Though some interspecies variations were observed, the convoluted portions of the proximal tubules revealed quite uniformly very leaky tight junctions with mainly 1–2 strands. Along the whole proximal tubule of the rabbit kidney including the pars recta only minor differences of the zonulae occludentes were found. By contrast, the tight junctions of the pars recta in other species were much more elaborate, especially in cat and tupaia, having up to 6 strands and an overall depth of more than 150 nm. The implications of these findings are discussed with special regard to the functional differences between the pars convoluta and pars recta of the proximal tubule.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 238 (1984), S. 413-416 
    ISSN: 1432-0878
    Schlagwort(e): Peroxisomes ; DAB-cytochemistry ; Electron microscopy ; Liver, amphibian ; Gymnophiona ; Ichthyophis glutinosus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of hepatic peroxisomes was investigated in Ichthyophis glutinosus (Amphibia: Gymnophiona), employing perfusion fixation and the diaminobenzidine (DAB) technique for the visualization of catalase. The majority of peroxisomes is circular or rod-shaped, although elongated particles occasionally occur. They contain a finely granular matrix, lightly stained after the DAB procedure. Their mean diameter is approximately 0.25 μm. Serial sections reveal that the circular and rod-shaped peroxisomal profiles are cross and oblique sections of highly tortuous, tubular organelles exceeding 2 μm in length. In addition to tubular profiles, elongated, rectangular particles, as well as straight dumbbell-shaped organelles with distinct marginal plates are observed. They range from 900 to 1650 nm in length (mean = 1200 nm). In the flattened, thin central portion of the dumbbell-shaped particle, the peroxisomal membranes form a cisterna enclosing one or two uniformly thick marginal plates, which display a definite substructure with a periodicity of 10 nm. These findings indicate that peroxisomes in the liver of Ichthyophis exhibit a complex organization. It is suggested that the organelles undergo a specific differentiation process, morphologically characterized by the formation of enlarged segments of unusual shape.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 187 (1978), S. 457-472 
    ISSN: 1432-0878
    Schlagwort(e): Ovarian follicles (sheep) ; Theca interna ; Oestrogen ; Androgen ; Capillaries ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The theca interna of non-atretic ovarian follicles from 2.0 mm in diameter up to the stage shortly following ovulation was studied by light and electron microscopy. In follicles 〈3.0mm in diameter, the theca interna consisted of about 8–12 layers of flattened cells, together with many capillaries and small bundles of collagen. Two main forms of cellular differentiation were seen. These were towards either fibroblast-like cells or presumed steroidogenic cells whose cytoplasm contained large amounts of predominantly smooth tubular endoplasmic reticulum, to which some ribosomes were attached. The majority of cells were of relatively undifferentiated or intermediate structure. In larger follicles up to the early stages of oestrus the theca interna cells became larger and less flattened, and cells rich in tubular endoplasmic reticulum became proportionately more numerous. By 18 h after the onset of oestrus the theca interna was oedematous, and many cells possessed pseudopodia. Many cells also contained numerous lipid droplets, but there were no signs of thecal cell degeneration or death. Shortly after ovulation the basal lamina of the membrana granulosa was incomplete, and it became more difficult to distinguish between theca and granulosa layers. Structural heterogeneity, with two major cell types and cells of intermediate structure, was present at all stages. It was concluded that: (1) the theca interna of 2.0–2.9 mm follicles contained many cells whose structure was compatible with a steroidogenic capacity; (2) changes in the differentiated thecal cells up to the early stages of oestrus were quantitative rather than qualitative, and suggestive of an increased steroidogenic capacity; (3) the accumulation of lipid in many cells of the theca interna by 18 h after the onset of oestrus probably reflected a reduction in steroidogenic activity; and (4) there was no evidence of any structural specialization to facilitate the transport of steroids from the theca interna to the membrana granulosa.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 59
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 75-82 
    ISSN: 1432-0878
    Schlagwort(e): Drum muscles ; Piranha ; Degenerative changes ; Fine structure ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the posterior drum muscle of the piranha structural alterations are frequently observed. Electron microscopic studies revealed a disordering of the myofibrils in these regions, accompanied by conspicuous changes in the mitochondria. As the degree of disorder increases, the mitochondrial cristae initially swell to form vesicles. Eventually the mitochondria become filled with myelin-like lamellar structures, which in many cases coalesce to form a dense outer wall. A striking concentration of lysosomes into localized masses was also characteristic of these regions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 167-177 
    ISSN: 1432-0878
    Schlagwort(e): Hypodermis ; Rotifer ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The integument of the rotifer Habrotrocha rosa Donner is provided with pores and formed by an extrasyncytial cuticle and a syncytial hypodermis. The hypodermis peripherally contains 3 layers of dense cytoplasm and borders the cuticle by an asymmetric cell membrane. The wall of the pores is stiffened proximally like an annulus. The pores lead into cytoplasmic invaginations which are surrounded by vesicles. Close to and also beneath the condensed cytoplasmic layers microbodies are found, which are interpreted as microperoxisomes. Subhypodermal layers of muscles are connected with the cytoplasm of the hypodermis by desmosome-like structures.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 257-266 
    ISSN: 1432-0878
    Schlagwort(e): Neuromuscular junction ; Hindgut ; Crustacea ; Catecholamine ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The crustacean species Pacifastacus leniusculus and Gammarus pulex were investigated by electron microscopy in a search for possible neuromuscular junctions in the hindgut, which has a rich supply of catecholaminergic fibres. True neuromuscular synapses were found in both species between nerve terminals containing dense-core vesicles (80–110 nm in diam.) and muscle fibres. We suggest that the dense-core vesicle terminals contain a catecholamine, and this is supported by ultrahistochemical tests for monoamines. Two types of junctions are found: one in which the nerve terminal is embedded in the muscle cell (both species) and one in which protrusions from the muscle cell meet nerve terminals (Pacifastacus). Gammarus pulex, which has only circular muscles in the hindgut, has only catecholaminergic innervation, whereas Pacifastacus leniusculus has circular and longitudinal muscles both with at least two types of innervation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 277-286 
    ISSN: 1432-0878
    Schlagwort(e): Maternal adrenalectomy ; Rat ; Influence on the adrenals of newborn animals ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Maternal adrenalectomy at 7 or 14 days of gestation produced increased cell necrosis within zona reticularis cells on the day of birth and at 24 or 48 h after birth. Small remnants or large portions of adrenocortical cells were present within macrophages. In otherwise normal adrenocortical cells, lipid droplets were incorporated within some mitochondria. Autophagocytosis of single mitochondria was observed within adrenocortical cells. Undoubtedly ultrastructural changes represent stimulation of adrenocortical cells in neonatal rats in response to maternal adrenalectomy.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 63
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 191 (1978), S. 449-462 
    ISSN: 1432-0878
    Schlagwort(e): Ileum (Rat) ; Occluding junctions ; Freeze-fracture ; Ultrastructure ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Two kinds of occluding junctions are found between ileal epithelial cells of suckling rats: apical zonulae occludentes (ZO) and fasciae occludentes (FO) which are associated with the lateral plasma membranes of many epithelial cells. In unfixed preparations, glycerol treatment induces the further proliferation of extensive fasciae occludentes. Both kinds of junction have identical structural elements when visualized in freeze fracture replicas, although the arrangement of these elements differs. Zonulae occludentes consist of networks of branching and anastomosing linear ridges or rows of ∼10 nm particles with 20–30 nm spaces between the rows which form narrow belt-like structures around the apical region of adjacent cells. Fasciae occludentes, on the other hand, consist of similar linear ridges or rows of particles but the junction strands are often discontinuous, open ended and only occasionally intersect with each other. Several different fracture planes through the plasma membrane in the region of the occluding junctions have been observed and these provide further evidence that two components, one from each membrane, fused at the level of the extracellular space, form the junction sealing element. Furthermore, we present evidence which indicates a staggered rather than an in-register arrangement of these two components.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 64
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 192 (1978), S. 39-51 
    ISSN: 1432-0878
    Schlagwort(e): Prostate ; Rat-Anti-Androgens ; Nuclear alterations ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of the nuclei of epithelial cells of the dorsal lobe of the rat prostate were studied after administration of three different antiandrogenic compounds. The nucleolus appears to undergo a progressive disorganisation with partial fragmentation and dispersion of its normal components. Different types of intranuclear inclusions were found. The various alterations observed were often encountered within the same section. This may indicate that the nuclear alterations occur in the same compartment of the cell, and represent a dysfunction of integrated biochemical events occurring within this compartment. The findings support a view that the stimulatory secretory effect of androgens is mediated via a ‘secretory center’, located within the nucleolusassociated chromatin. Within this ‘secretory center’, the initial steps of the secretory process, the binding of the DHT receptor complex to DNA is assumed to occur.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 65
    ISSN: 1432-0878
    Schlagwort(e): T-lymphocytes ; Stereological model system ; Free cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Menschliche, in Nylonwolle gereinigte T-Lymphozyten aus dem peripheren Blut dienten als repräsentatives Untersuchungsobjekt zur Schaffung eines neuen stereologischen Modellsystems für freie, sphärische Zellen. Dieses System erlaubt, die Zelle und die darin enthaltenen Strukturkomponenten auf ultrastruktureller Ebene quantitativ zu charakterisieren.
    Notizen: Summary T-lymphocytes derived from human peripheral blood and passed through a nylon-wool column, were employed to develop and test a new Stereological model system for free spherical cells, allowing a quantitative characterization of the cell and its components at the ultrastructural level. Electron micrographs were recorded in a hierarchical manner at three different levels of magnification and subjected to point counting procedures. The resulting parameters were expressed in relation to various reference compartments, both absolute and relative. Results indicated that the average volume of a small, non-activated T-lymphocyte was 103.8 μm3, the nuclear volume 47.5 μm3 and the cytoplasmic volume 55.9 μm3. On the average, the cytoplasm contained 30 mitochondria, 0.7 μm3 RER-cisternae, 0.2 μm3 cisternae and vesicles of the Golgi apparatus and about 231,000 free ribosomes (most of them single). The ratio of eu- to heterochromatin volume was 0.5. The design and application of the Stereological model system are discussed with regard to dynamic studies of a variety of free cells, such as macrophages, neutrophilic granulocytes and various lymphocytes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 66
    ISSN: 1432-0878
    Schlagwort(e): Key words: Node of Ranvier ; Axon ; Horseradish peroxidase (HRP) ; Retrograde axonal transport ; Electron microscopy ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Horseradish peroxidase (HRP) was injected into the left dorsal column nuclei of adult cats. Large dorsal funiculi axons of the C3, C5, C8 and L7 segments were searched for HRP-activity after 12, 24, 36 and 48 h using light and electron microscopy. Accumulations of intra-axonal HRP-positive bodies occurred at nodes of Ranvier in the C3–C8 segments at 12, 24 and 36 h and in the L7 segments at 24, 36, and 48 h. The accumulations of HRP in three spatio-temporally different consecutive patterns, noted earlier at nodes of Ranvier in the peripheral nervous system (PNS) portion of feline alpha motor axons for more than 70 h after an intramuscular injection of the enzyme, were not observed in the present material. We suggest that the differences in the modes in which large PNS and CNS axons interact with retrogradely transported HRP are due to differences in the organization of the respective nodal regions. We also emphasize that endocytosis via axon terminals in the CNS normally represents uptake of material from an extracellular space which is controlled and protected by the blood-brain barrier. This is in contrast to endocytosis via axon terminals in a muscle, which represents uptake of material from an extracellular space openly exposed to influx of different substances from the blood stream.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 67
    ISSN: 1432-0878
    Schlagwort(e): Key words: Intracardiac neurones ; Innervation ; Heart ; Neuropeptide Y ; Immunocytochemistry ; Electron microscopy ; Rat (Sprague Dawley) ; Guinea-pig (Dunkin Hartley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Intrinsic neuropeptide Y-containing neurones in rat and guinea-pig hearts were studied at the ultrastructural level by the pre-embedding peroxidase-antiperoxidase immunocytochemical technique. Intracardiac neuronal cell bodies were often weakly or moderately immunostained, and the labelling was usually pronounced in the Golgi complex, multivesicular bodies, some cisterns of granular endoplasmic reticulum and large granular vesicles. Neuropeptide Y-immunoreactive nerve fibres were also observed in association with intracardiac neurones. A subpopulation of neuropeptide Y-immunoreactive granule-containing cells in the rat heart are described for the first time and were very heavily labelled; other granule-containing cells were non-immunoreactive, but were contacted by neuropeptide Y-containing nerves. Preterminal regions of nerve fibres that were located in nerve bundles were only weakly neuropeptide Y-immunoreactive, in contrast to the heavy labelling observed in varicosities that contained many synaptic vesicles. Many neuropeptide Y-immunoreactive nerve fibres were associated with the coronary vasculature and were particularly prominent in the walls of small arteries and arterioles where labelled nerve varicosities were present close to the smooth muscle cells. Immunoreactive nerves were also seen in the myocardium, usually near to capillaries. In axonal varicosities, the central core of large granular vesicles was immunolabelled, and electron-dense immunoreactive material outlined the membranes of small and large clear vesicles. The significance of neuropeptide Y-immunoreactive intracardiac neurones and granule-containing cells and the origin of associated labelled nerve fibres in the heart are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 68
    ISSN: 1432-0878
    Schlagwort(e): Ovulation (rabbit) ; Graafian follicle ; Perfusion ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Isolated ovaries from untreated, sexually mature rabbits were introduced into an in vitro perfusion system and perfused with a chemically defined medium containing albumin. The ovaries were perfused for up to 15 h (mean 11.5 h) and then processed for morphological investigation. Both at the light- and electron-microscopical levels, most of the ovaries exhibited a normal structure comparable with ovaries in situ. In two cases, however, marked accumulations of bacteria were found, although not inside the follicles. Since ovulation in the rabbit normally occurs between 9.5–13 h after mating or human chorionic gonadotrophin treatment, this model seems adequate for studies of ovulation in vitro. It is, however, important to study the ovaries microscopically after the perfusion to detect artifacts, e.g., bacterial infection, that may have influence on the process of ovulation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 69
    ISSN: 1432-0878
    Schlagwort(e): Tannic acid ; Acetylcholine receptors ; Tissue culture ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Spinal cord neurons from 9-day chick embryos were maintained in culture for up to 35 days and then fixed in 4% cacodylate-buffered glutaraldehyde containing 2% tannic acid. After about 15 days in culture a small percentage of the synaptic specializations present were characterized by striking electron-dense striations averaging 15 nm in width, oriented perpendicular to the postsynaptic membrane. These structures increased in frequency with time in culture (to a maximum of about 10% of all synapses in the oldest cultures); they were asymmetrical, protruding approximately 8 nm into the synaptic cleft, and more deeply (approximately 15–18 nm), into the postsynaptic cytoplasm. On the basis of earlier work by Sealock (1980) they are interpreted as concentrations of acetylcholine receptors. Similar membrane differentiations were also seen associated with active-zone areas of a few presynaptic membranes, and the possibility that these represent presynaptic acetylcholine receptors is discussed. Additional observations reported are (1) the presence of striations resembling those seen at the postsynaptic membrane in the membranes of some postsynaptic vesicles, and (2) filamentous links between the striations and cytoskeletal elements of the postsynaptic cell.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 70
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 235 (1984), S. 479-484 
    ISSN: 1432-0878
    Schlagwort(e): Monoamine-containing cells ; Taste bud ; Paracrine cells ; Mechanoreceptors ; Electron microscopy ; Teleosts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The taste buds on the barbels in three species of teleosts (Cyprinus carpio, Misgurnus anguillicaudatus, Parasilurus asotus) were studied by means of fluorescence and electron microscopy. Intensely yellow-fluorescent cells, which are disk-shaped and located exclusively in a basal position, are observed in the barbel-buds of all fishes examined. The basal cells contain a large number of small clear vesicles approximately 40–60 nm in diameter, which show a tendency to aggregate in the cytoplasm facing the junction of the nerve terminals; chemically transmitting synapses are seen in the latter region. It is suggested from the present observations that the basal cells in the barbel-bud may originate from Schwann cells and have a dual function both as mechanoreceptors and paracrine elements. Since the administration of 5,6-DHT results in an appearance of small dense vesicles among the small clear vesicles, the possibility exists that the basal cell may be capable of taking up monoamines and storing them in the small clear vesicles.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 71
    ISSN: 1432-0878
    Schlagwort(e): Exocrine pancreas ; Calcium pool ; Calcium release ; Electron microscopy ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In an attempt to identify a cellular Ca2+-pool, from which calcium is released when secretagogues are applied, tissue fragments of the rat exocrine pancreas were incubated and fixed with glutaraldehyde in the presence of calcium. By means of this procedure electron-dense deposits were found on plasma membranes. X-ray microanalysis showed that these deposits contain calcium. Stimulation of tissue fragments with the use of the secretagogues carbachol or cholecystokinin reduced the number of deposits by about 80%. When the antagonist atropine was applied after carbachol stimulation, deposits reappeared on cell membranes, which then disappeared again after a second stimulation with cholecystokinin. In the presence of procaine, carbachol was inhibited and only slightly reduced the Ca2+-deposits on the plasma membranes. These results suggest that a calcium pool, from which calcium is released to induce enzyme secretion on stimulation, is located in the cell membrane
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 72
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 199 (1979), S. 171-175 
    ISSN: 1432-0878
    Schlagwort(e): Crustaceans ; Neuromuscular synapse ; Multiterminal innervation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The distribution of nerve terminals from a single excitatory motor axon has been followed along a fiber from the proximal accessory flexor muscle of the lobster by thin serial sectioning at periodic intervals. The excitatory motor axon provides small axonal branches (diameter 5–12 μm) of varying lengths that travel along the surface of the muscle fiber. Each of these branches gives rise to discrete synaptic terminals which are not uniformly distributed. Individual terminals vary in length from 10–60 μm and the majority possess neuromuscular synapses. The greatest distance between synapses is slightly over 1 mm which is well within the length constant (2.6 mm) of this muscle fiber. Thus the spatial distribution of synapses is such as to ensure adequate depolarization along the entire length of the muscle fiber.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 73
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 199 (1979), S. 281-288 
    ISSN: 1432-0878
    Schlagwort(e): Annular microtubules ; Nodes of Ranvier ; Nerve ; Axon ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Using a special albumin technique, nodes of Ranvier have been examined within frog skeletal muscle, sciatic nerve and rat and frog cerebrum. Initial segments have been examined in cerebrum of frog and rat. Microtubules usually run longitudinally through these regions, but within the bare area of the intramuscular node of Ranvier, annular or helical bundles of microtubules run in a marginal band at right angles to the more centrally placed longitudinal microtubules. These nodal bare areas show a pronounced convexity and it is suggested that the annular microtubules serve to maintain this convexity during muscle contraction.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 74
    ISSN: 1432-0878
    Schlagwort(e): Chloride cells ; Acid stress ; Gill ; Electron microscopy ; Fathead minnow
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Fathead minnows, Pimephales promelas, were exposed for 129 days to Lake Superior water acidified with sulfuric acid by means of a flow-through toxicant injection system. The effects of chronic acid stress (pH 6.5, 6.0, 5.5, 5.0) on gill histology were examined. Most of the histological effects were seen at pH 5.5 and 5.0 and were confined primarily to changes in numbers, distribution, and morphology of chloride cells. At low pH levels there tend to be more chloride cells in the gill epithelium and an increased percentage of these cells in the secondary lamellae. In contrast to normal chloride cells, chloride cells from fish exposed to low pH frequently had apical pits while some had bulbous apical evaginations. The occurrence of structural changes in chloride cells during exposure to acid water suggests that chloride cells may be involved in acclimation to acid stress.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 75
    ISSN: 1432-0878
    Schlagwort(e): Lactating cell ; Lipid droplets ; Secretory vesicles ; Mitochondria ; Intracellular associations ; Electron microscopy ; Milk secretion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The size, cellular location, and identity of surface-associated components were determined for lipid droplets in lactating cells. Transmission electron-microscopic measurements were made involving 3801 droplets in approximately 211 cells from three rats and 1197 droplets in 66 cells from a mouse. For the purposes of droplet evaluation, cells were divided into seven locations ranging from basal to secreting positions. Droplets were also categorized with respect to contact with other droplets, basolateral plasma membrane, mitochondria, Golgi apparatus, secretory vesicles, and endoplasmic reticulum-cytoplasm (ERC). Data on droplet size showed that droplet growth occurs mainly in the secretory position, confirming previously published findings. Lipid droplets from mouse tissue, although somewhat smaller in size showed similar growth trends to those of the rat. Data on numbers of droplet contacts and percentages of droplet circumferences involved in associations with other cell components showed that the dominant interaction of lipid droplets was with the ERC. However, intimate association of droplets with mitochondria was noted in all cellular locations. In addition, nursed animals exhibited a greater proportion of droplet surface association with secretory vesicles and less in contact with mitochondria in comparison to those not nursed. The significance of these relationships to milk synthesis and secretion is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 76
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 236 (1984), S. 249-255 
    ISSN: 1432-0878
    Schlagwort(e): Oocyte ; Nucleolus ; Silver staining ; Electron microscopy ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The nucleoli of dictyate-stage growing oocytes in rat ovaries were examined both with routine electron microscopy and electron microscopy after silver nitrate and ammoniacal silver nitrate (Ag-AS) staining. The nucleoli of the unilaminar follicular oocytes consist of twisted strands of dense fibrillar components, aggregates of granular components, and small fibrillar centers. After Ag-AS staining, silver grains are numerous on the dense fibrillar strands, fewer on the fibrillar centers, and very sporadic on the granular aggregates. The same stainability of three nucleolar components with the Ag-AS method was also confirmed in the nucleoli segregated by actinomycin D. During the transition of growing oocytes from bilaminar to plurilaminar follicle stage, the nucleolar dense fibrillar strands gradually conglomerate and are transformed into large and compact spherules. The stainability of dense fibrillar components with the Ag-AS method was lost along with this nucleolar transformation. These results may provide some new clues on the functional significance of AgAS-positive proteins in the nucleoli.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 77
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 201 (1979), S. 37-44 
    ISSN: 1432-0878
    Schlagwort(e): Brush cell ; Receptor ; Lateral microvilli ; Gallbladder ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The brush cells of the gallbladder epithelium of the mouse have microvilli not only at their luminal border but also on their lateral surface, from the level of the nucleus to the junctional complex. The lateral microvilli radiate from the brush cell in all directions, contain a core of filaments, and penetrate up to 3 μm into the adjacent cells. The microvilli in these locations display small desmosomes at their base.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 201 (1979), S. 451-458 
    ISSN: 1432-0878
    Schlagwort(e): Epididymis ; Freeze-fracture ; Electron microscopy ; Male reproduction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The epithelium of the monkey epididymis was studied by means of freeze-fracture techniques and conventional electron microscopy. For the study of transepithelial permeability lanthanum hydroxide was used as an intercellular tracer. The epididymal epithelium consists mainly of tall columnar cells. The long stereocilia at the apical surface, similarly to microvilli, exhibit after freeze-fracture, two distinct faces: the E face, concave and with fewer membrane-associated particles, and the complementary convex P face. In the lumen unusual groups of smooth-surfaced vacuoles are present. A tight junctional network, which shows some permeability to the lanthanum tracer, is located at the apical end of the cells. Supranuclear cross-fractures clearly show the well developed Golgi cisternae and numerous vacuole profiles. The highly infolded, centrally located nucleus exhibits, after freeze-fracture, an even distribution of nuclear pores. In the perinuclear region the rough endoplasmic reticulum, which also presents pores, displays a sheet-like organization. The basal cytoplasm is filled by numerous globular profiles of membrane-bounded granules. Freeze-cleave exposes large cytoplasmic areas where the types and amount of organelles indicate an intense metabolic activity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 201 (1979), S. 467-477 
    ISSN: 1432-0878
    Schlagwort(e): Anterior pituitary ; Hormone synthesis ; Morphometry ; Autoradiography ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In order to compare the functional state of the anterior pituitary of spontaneously hypertensive rats (SHR) with that of normotensive Wistar Kyoto rats (WKR), the anterior pituitary was examined by morphometry and autoradiography at the level of electron microscopy. The relative number and the relative volume of thyrotrophs in the anterior pituitary were significantly greater in SHR compared with age-matched WKR at 0, 7, 30–33 days, and 10 months of age, while the relative number of somatotrophs in SHR was significantly smaller at 1 and 10 months of age. Electron microscope autoradiographic analysis of uptake of 3H-lysine by thyrotrophs of both strains at the age of approximately one month showed that 3H-lysine was incorporated into protein and transported finally to secretory granules which migrated to near the cell membrane to be discharged. Silver grains were significantly more numerous over the thyrotrophs of SHR than over those of WKR at 30 min, 1 h, and 4h after the injection of 3H-lysine. The present study has ascertained morphologically that a congenital hypersynthesis of TSH by the anterior pituitary occurs in SHR.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 80
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 202 (1979), S. 125-132 
    ISSN: 1432-0878
    Schlagwort(e): Macrophage ; Osteoclast ; Bone resorption ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ultrastructural observations on macrophage-mediated resorption of calcified tissue of killed fetal long bones are described and correlated with increased 45Ca release into the medium. Macrophages disrupt calcified tissue extracellularly and appear to engulf large fragments of mineralized matrix. Ruffled borders, which are common features of osteoclasts at sites of resorption of bone, do not develop in macrophages. However, clear zones are seen in macrophages as well as osteoclasts. These findings provide additional evidence for non-osteoclast-mediated resorption of calcified tissue.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 81
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 186 (1978), S. 535-540 
    ISSN: 1432-0878
    Schlagwort(e): Skeletal muscle ; Satellite cells ; Regeneration ; Electron microscopy ; Autoradiography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Satellite cells were traced autoradiographically during the regeneration of skeletal muscle in young Sprague-Dawley rats. Approximately 31% of the satellite cells in uninjured muscles appeared labelled after three injections of tritiated thymidine; none of the myonuclei were labelled in the same muscles. Four to six days after transplanting the radioactive muscles to non-radioactive littermates, regenerating myotube nuclei in the host appeared labelled. Thus, this study confirms that satellite cells in young rats can differentiate into multinucleated myotubes following muscle injury.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 82
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 187 (1978), S. 159-165 
    ISSN: 1432-0878
    Schlagwort(e): Endocrine cells ; Ascidian (Styela clava) ; Gut epithelium ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ultrastructural studies have shown the presence of two types of granulated endocrine cell in the gut of Styela clava. Type I, which occurs in the stomach and intestine contains small irregular granules, each with a distinct halo. Type II, found only in the oesophagus contains larger rounded granules, often with little or no halo. The characteristics of these two cell types are compared with those of endocrine cells found in the digestive tracts of other protochordates and discussed with special reference to the evolution of gastrointestinal endocrine cells in vertebrates.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 83
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 187 (1978), S. 439-448 
    ISSN: 1432-0878
    Schlagwort(e): Urinary bladder epithelium (Rat) ; Gap junctions ; Tight junctions ; Electron microscopy ; Freeze-fracturing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The junctional connections between the cells of the urinary bladder epithelium in rat have been studied by freeze-fracturing. Tight junctions and desmosomes are known as structural features of the epithelium. In addition, gap junctions (nexus) have been found to connect the epithelial cells in an irregular distribution pattern. The junction size ranges from few assembled particles up to plaques with irregular forms. This may indicate that the gap junctions are mobile structures. The functional significance of the junctions in comparison with electrophysiological data is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 84
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 497-508 
    ISSN: 1432-0878
    Schlagwort(e): Fertilization ; Domestic fowl ; Acrosome reaction ; Vitelline membrane ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The developing outer layer of the vitelline membrane of the ovum in the posterior part of the infundibulum of the domestic fowl contains many spermatozoa in nearly parallel orientation with its inner layer. When the acrosomal region of a spermatozoon approaches or contacts the inner layer, promptly undergoes the acrosome reaction. The outer acrosomal membrane and overlying plasma membrane fuse together and the apical region of the acrosome opens, so that the acrosomal contents are released. Meanwhile the spermatozoon remains a time in contact with the surface of the inner layer, and the network of the inner layer just under the tip of the sperm head begins to be dissolved. This dissolution extends downward forming a tunnel, approximately 9 μm in diameter. The spermatozoon then passes through the inner layer obliquely via the central region of the tunnel and arrives at the perivitelline space.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 85
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 375-388 
    ISSN: 1432-0878
    Schlagwort(e): Lateral line organ ; Pit organ ; Sea eel (Conger myriaster) ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of the pit organ of the sea eel has been studied by means of electron microscopy. The sensory epithelium of the pit organ consists of sensory cells and supporting cells. The apical surface of the sensory cell is studded with sensory hairs consisting of a kinocilium and stereocilia. The sensory cells are divided into two groups. In one, the kinocilium points dorsally and in the other the kinocilium points ventrally. The total number of sensory cells in one pit organ is about 100, and the ratio of cells with opposite polarity is about 1∶1. On the basis of these structural features, the pit organ is considered to be a mechano-receptor sensitive to the movement of liquid in a dorso-ventral direction. It may also serve as an ion receptor, sensitive to environmental ion concentration. Efferent nerve terminals make rare synaptic contacts on the afferent nerve fiber.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 86
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 515-523 
    ISSN: 1432-0878
    Schlagwort(e): Protonephridium ; Rotifer ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The excretory system of Habrotrocha rosa consists of two protonephridia. From each of them seven tubules lead to a terminal organ, also called cyrtocyte. Its weir basket contains structures which resemble ciliary rootlets. The lumen of the excretory system is bordered by a syncytial layer of cytoplasm. Cells are only found in the upper region of the trunk, where the channel is twisted several times.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 87
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 525-535 
    ISSN: 1432-0878
    Schlagwort(e): Alimentary system ; Rotifer ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The alimentary system of Habrotrocha rosa is composed of the alimentary channel, five digestive glands and another gland which is in close relation to the intestinal syncytium. After the present investigation, the alimentary channel can be divided into sections which clearly differ from each other, these are: oral cavity, pharynx, oesophagus, mastax, stomach-hose, syncytium of intestine, and terminal intestine.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 88
    ISSN: 1432-0878
    Schlagwort(e): Key words: Lateral heart nerve ; FMRFamide ; Allatostatin ; Coexistence ; Mirror-section ; Axosomatic synapses ; Electron microscopy ; Periplaneta americana (Insecta)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Both allatostatin immunoreactivity (AS-IR) and FMRFamide immunoreactivity (FMRFa-IR) have been demonstrated light-microscopically in the lateral heart nerve of Periplaneta americana. The identical labeling of some fibers suggests the coexistence of the two antigens. Electron-microscopically, six granule types in the peripheral part of the lateral heart nerve can be distinguished according to their size and density (types 1–6). These granule types can be subdivided immunocytochemically by means of a new mirror-section technique. Granules of types 4 and 5 always exclusively show FMRFa-IR. In the populations of fibers containing granules of types 1 and 6, axon profiles can be found that contain granules colocalizing FMRFa-IR and AS-IR. Other axon profiles of these populations only contain immunonegative granules of the same ultrastructure. Granules of type 2 can be differentiated immunocytochemically in three forms in the same section: In some fibers, they are nonreactive; in other fibers of the same section, they show FMRFa – IR, whereas in a third fiber type, granules show AS – IR. Finally, granules of type 3 can be observed with FMRFa-IR. In other fibers, they occur with the same ultrastructure but exhibit no immunoreactivity. Two soma types occur in the lateral heart nerve. Soma type I is characterized by the production of electron-dense granules that show FMRFa-IR. Type II is in close contact with various fibers, forming different types of axosomatic synapses, hitherto unknown in Insecta.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 89
    ISSN: 1432-0878
    Schlagwort(e): Key words: Spermatozoa ; Acrosome ; Thiols ; Disulphides ; Electron microscopy ; Monomaleimido nanogold ; Macropus eugenii (Marsupialia)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. This study utilised a commercially available monomaleimido-nanogold reagent to directly label cellular thiol groups (SH) of marsupial (tammar wallaby) spermatozoa before and after reduction of disulphides (S-S) with mercaptoethylamine hydrochloride (MEA). The sperm surface, mitochondrial membranes, axoneme and tail fibres were all labelled with gold particles before MEA treatment and the label intensity was increased after S-S reduction. The acrosomal membranes and matrix of spermatozoa contained no detectable SH prior to MEA treatment. However, after moderate MEA treatment (1 mg/ml) gold label was associated with the acrosomal membrane and invaginated acrosomal membrane within the acrosomal matrix. After exposure to 5 and 10 mg/ml MEA, gold particles heavily labelled the acrosomal matrix. Thus, the acrosomal membranes and matrix of tammar wallaby spermatozoa both contain S-S cross-linked structures, and this may contribute to the unusual stability of the marsupial acrosome. Under all treatment conditions the nucleus remained unlabelled. This is consistent with early studies which indicated that cysteine was absent from the nuclear protamines. The study also demonstrated that monomaleimido-nanogold can be used to resolve SH- and S-S-rich cellular structures directly, in addition to its use to label antibodies and Fab fragments for immunochemical localisation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 90
    ISSN: 1432-0878
    Schlagwort(e): Somatotrophs ; Growth hormone ; Growth hormone-releasing factor ; Secretory granule ; Electron microscopy ; Morphometry ; Rat (Fischer 344)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The anterior pituitary tissue of male rats injected with growth hormone-releasing factor (GRF) was either processed for stereology at the light-and electron-microscopic levels, or homogenized for growth hormone (GH) assay 2–60 min after GRF injection. Secretory granules of somatotrophs became smaller but increased in numerical density 2 min after GRF injection. Their volume density began to increase at 5 min. The frequency of exocytosis of the granules was most prominent as early as 2 min after GRF injection and reduced thereafter. GH levels in the tissue were lowest at 2–5 min, and returned to the control value by 60 min. Serum GH levels were highest at 15 min; even at 60 min, this value was higher than in the controls. These findings suggest that secretory granules in somatotrophs are stimulated to divide by GRF, resulting in a decrease in size and an increase in number. The discrepancy between the earlier formation of new secretory granules and the later restoration of intracellular GH levels implies that GRF first stimulates the synthesis of constituents of granules other than GH, and only later the synthesis of GH, and that newly formed small secretory granules contain less GH. From the clearance rate of serum GH and the frequency of granule exocytosis, it can be estimated that about a half million granules are released to maintain 1 ng/ml of serum GH in rats.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 91
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 280 (1995), S. 183-188 
    ISSN: 1432-0878
    Schlagwort(e): Blood platelets ; Oxidized LDL ; Cytochalasin D ; Reflection contrast microscopy ; Image analysis ; Electron microscopy ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The adhesion of human blood platelets is studied with an in vitro model using reflection contrast microscopy and an image analysis system. The adhesive feature is promoted by oxidatively modified low density lipoprotein, which also induces functional morphological changes of platelets. However, when washed platelets are pretreated with 0.05 mM cytochalasin D, oxidized low density lipoprotein (100 μg/ml) causes a slower increase of the adhesion area (11.6 μm2/min) compared to untreated platelets (15.7 μm2/min) or platelets treated by oxidized low density lipoprotein alone (20.5 μm2/min, P〈0.01). These results are supported by light transmission analysis and by transmission electron microscopy. Our experiments suggest that cytochalasin D inhibits the change of platelets in shape induced by oxidized low density lipoprotein, hinders the adhesion, but does not prevent the adhesion entirely.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 92
    ISSN: 1432-0878
    Schlagwort(e): Nitric oxide synthase ; Vasoactive intestinal peptide ; Immunohistochemistry ; Electron microscopy ; Submucous plexus ; Guinea-pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract In the submucous plexus of the guinea-pig ileum, previous light-microscopic studies have revealed that vasoactive intestinal peptide (VIP)-immunoreactive and nitric oxide synthase (NOS)-immunoreactive terminals are found predominantly in association with VIP-immunoreactive nerve cell bodies. In this study, double-label immunohistochemistry at the light-microscopic level demonstrated co-localization of NOS-immunoreactivity and VIP-immunoreactivity in axon terminals in submucous ganglia. About 90% of nerve fibres with NOS-immunoreactivity or VIP-immunoreactivity were immunoreactive for both antigens; only about 10% of labelled varicosities contained only NOS-immunoreactivity or VIP-immunoreactivity. The VIP/NOS varicosities were more often seen in the central parts of the ganglia, close to the VIP-immunoreactive cell bodies. Ultrastructural immunocytochemistry with antibodies to VIP was used to determine if NOS/VIP terminals synapse exclusively with VIP-immunoreactive nerve cell bodies. We examined the targets of VIP-immunoreactive boutons in two submucous ganglia from different animals. Serial ultrathin sections were taken through the ganglia after they had been processed for VIP immunocytochemistry. For each cell body, the number of VIP inputs (synapses and close contacts) was determined. The number of VIP-immunoreactive synapses received by the cell bodies of submucous neurons varied from 0–4 and the number of VIP-immunoreactive close contacts varied from 3–10. There was no significant difference between VIP-immunoreactive nerve cell bodies and non-VIP nerve cell bodies in the number of VIP-immunoreactive synapses and close contacts they received. Thus, the implication from light microscopy that NOS/VIP terminals end predominantly on VIP nerve cells was not vindicated by electron microscopy.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 93
    ISSN: 1432-0878
    Schlagwort(e): Key words: Quinolinic acid ; Interferon-γ ; Kynurenine ; Electron microscopy ; Immunocytochemistry ; Excitotoxicity ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract.  Quinolinate (QUIN), a tryptophan-derived excitotoxin, was localized ultrastructurally in human peripheral blood monocytes/macrophages (MØ) by immuno-electron microscopy. A combined carbodiimide/glutaraldehyde/paraformaldehyde-based fixation procedure was developed for optimal retention of QUIN in the cell as well as minimal loss of ultrastructure; a silver-enhanced colloidal gold detection system was used for electron-microscopic analysis. Gold particles representing QUIN immunoreactivity were associated with the inner side of the plasma membrane in normal MØ. The number of gold particles increased significantly when QUIN levels were elevated by treatment with its precursor kynurenine, but location of the gold particles remained essentially the same under this condition. Treatment with interferon-γ increased the number of Golgi bodies, vacuoles and pseudopodia, reflecting the activated state of the cell. Significantly increased numbers of gold particles representing QUIN were detectable in approximately the same location as in the case of kynurenine treatment. Combined treatment with kynurenine and interferon-γ maximally increased the number of gold particles at the periphery of the cell. The pseudopodia were intensely stained with gold particles, while they were not detectable in the inner part of the cytoplasm or in any other organelle even under this activated condition. The significance of the specific location of QUIN revealed in the present study and its relation to the release and subsequent actions of QUIN are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 94
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 289 (1997), S. 517-526 
    ISSN: 1432-0878
    Schlagwort(e): Key words: Neuromuscular junction ; Synaptic vesicles ; Vesicle fusion ; Electron microscopy ; Callinectes sapidus (Crustacea)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Neuromuscular terminals of a single motoneuron to four muscles (CPV7a, GM5a, CV2, and CV3) in the stomach of the blue crab Callinectes sapidus showed structural evidence for the exocytotic release of dense-core vesicles exclusively at synapses. The primary evidence was the appearance of dense cores in the synaptic cleft, accompanied by indentations of the presynaptic or postsynaptic membrane. In their simplest form, these consisted of an omega-shaped figure of the presynaptic membrane enclosing one dense core, denoting release of a single dense-core vesicle. A larger indentation of the presynaptic membrane enclosing several dense cores denoted multiple release. A more complex form of multiple release was where the presynaptic membrane was normal, but the postsynaptic membrane elaborated into a sac projecting into the granular sarcoplasm and filled with dense cores. The postsynaptic sac in some instances was compressed into a thin, fingerlike extension, which lacked dense cores and, at its distal end, separated into small cisternae, suggesting a mechanism for membrane recycling. Profiles depicting single and multiple releases of dense-core vesicles were found more frequently at neuromuscular terminals that release relatively large amounts of transmitter with a single stimulus, such as CV2 and CV3, compared to those releasing smaller amounts, such as CPV7a and GM5a. The disparity in release sites among the four muscles of this single motor unit and the fact that many of the multiple-release figures were closely adjacent to the active zones for transmitter release suggest a possible modulatory role for dense-core vesicles in synaptic transmission. Such modulation may be long lasting, as implied by the postsynaptic sacs, which may permit prolonged release of the contents of their dense cores into the synaptic cleft. This is in keeping with the functional role of these stomach muscles, which is to be continuously active for long periods of time.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 95
    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
    BibTip Andere fanden auch interessant ...
  • 96
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 235 (1984), S. 153-158 
    ISSN: 1432-0878
    Schlagwort(e): Bovine ; Interdigitating cell ; Lymphoid tissues ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Electron-microscopic studies of lymphoid tissues from bovine fetuses and from calves disclosed a non-lymphoid cell type in the thymus-dependent zones of secondary lymphoid tissues and in the thymus that is distinguishable from reticulum cells, epithelial and endothelial cells, and macrophages. Based on morphological and topographical criteria, the cell is identified as the interdigitating cell. In addition, studies of the tissues of normal and virus-challenged fetuses, and of conventionally reared calves, indicated that the interdigitating cells originate from monocytoid cells, which undergo differentiation in the thymus-dependent zones during an immune response.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 97
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 235 (1984), S. 243-249 
    ISSN: 1432-0878
    Schlagwort(e): Gap junction ; Electron microscopy ; Freeze fracture ; Cell-to-cell communication
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Gap junctions exist in the septa between the segments of the lateral giant axons in the ventral nerve cord of the crayfish Procambarus. A large increase in the resistance (uncoupling) of these gap junctions was brought about by mechanical injury to the axonal segments. Both thin sections and freeze-fracture preparations were used to monitor the morphological changes which occurred up to 45 min after injury. There was no apparent change in the organization (a loose polygonal array) of the intramembrane particles which make up the junctional complex up to 45 min after injury. In some instances, however, the intramembrane particles appeared to have moved away from the junctional area. Other junctional regions were internalized and appeared similar to what have been called annular gap junctions. Also at this time (20–25 min after injury), a dense cytoplasmic plug formed in uninjured axon near the junctional region. It is concluded that the gap junctions that exhibit a loose polygonal organization of the intramembrane particles may be either in a state of low resistance (coupled) or a state of high resistance (uncoupled).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 98
    ISSN: 1432-0878
    Schlagwort(e): Ovulation ; Perfusion ; Graafian follicle (rabbit) ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ovulation was induced in rabbits by intravenous administration of human chorionic gonadotrophin (HCG), and 4–5 h later the ovaries were isolated and introduced into an in-vitro perfusion system containing synthetic medium with albumin. Rupture of follicles occurred in vitro within the physiological time range (mean 11.3 h after injection of HCG), although with a reduced frequency. Preovulatory and ruptured follicles were studied in detail by light and electron microscopy. In the granulosa layer of ruptured or preovulatory follicles cytoplasmic blebbing activity, disappearance of CallExner bodies and differentiation toward luteinized cells were found. Perhaps the most important sign of normal preovulatory development in vitro was that the basement membrane surrounding the granulosa layer was penetrated by projections of granulosa cells. In the absence of this penetration phenomenon the granulosa layer prolapsed out of the follicle. Immediately before rupture, follicles showed marked degeneration, restricted to the outer layers of the apical wall, which is compatible with the hypothesis that degradative enzymes are released close to the surface of preovulatory follicles. Although the majority of follicles that ovulated under in-vitro conditions showed the same kind of morphological alterations as can be seen in vivo, occasional atypical ruptures occurred without any overt signs during perfusion. Also technical manipulations of the perfusion system, e.g., nonphysiological increase of perfusion pressure, could force follicles to rupture. This illustrates the importance of careful morphological study of all ovaries perfused in vitro before conclusions are drawn.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 99
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 237 (1984), S. 149-154 
    ISSN: 1432-0878
    Schlagwort(e): Pituitary gland, pars distalis ; Innervation ; Synaptoid contacts ; Electron microscopy ; Rana temporaria L
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the pars distalis of the hypophysis of adult Rana temporaria, three types of nerve-fiber profiles were found at two distinct sites, in both lateral parts of the bordering regions of the anterior lobe with the intermediate lobe of the hypophysis. The first type of nerve-fiber profile consists of bundles of very fine axonal elements (diameter: 〈0.7 μm). The second type is formed by larger nerve fibers (diameter up to 4 μm) containing a few neurosecretory granules of approximately 100 nm. The third type of nervefiber profile resembles the second type but these nerve fibers make synaptoid contacts on at least two different types of glandular cells. The possible functional significance of these nerve fibers in the pars distalis is discussed. No nerve fibers were found (1) in the central part of the bordering region of the pars distalis with the intermediate lobe, (2) at the bordering region with the median eminence and (3) with the neurohypophysial stalk, and (4) in all other parts of the pars distalis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 201 (1979), S. 101-127 
    ISSN: 1432-0878
    Schlagwort(e): T-lymphocytes ; Cell activation ; Stereology ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Stereological data of phytohaemagglutinin (PHA)-activated human T-lymphocytes were recorded at intervals (12 to 72 h) together with biochemical (isotope-uptake, lymphotoxin-release) and morphological measurements. About 98 % of the cells were activated 12 h after PHA-stimulation. The activation phase lasted less than 48 h, i.e., cells entering the activation phase within 12 h were at their activation maximum by 48 h. The activated cell increased in size. The nuclear/cytoplasmic-ratio decreased. Most of the cytoplasmic organelles developed in phase with the increase of cytoplasmic volume. After 48 h, mitotic figures were frequently seen. Due to the increasing number of secondary, activated daughter cells, parameters of most cytoplasmic components declined between 48 and 72 h. Structural changes in the nucleus preceded the 3H-leucine uptake, which had not reached its maximum after 72 h of incubation. The 3H-leucine uptake started as early as 12 h after culture initiation, and its increase was proportional to the increasing polyribosome density. No maximum uptake was reached up to 72 h, but the development of structural components related to this uptake was at its maximum at the end of the activation phase (48 h). The formation of bound ribosomes occurred subsequent to the enlargement of the surface of the rough endoplasmic reticulum. Initial polysome formation occurred at the expense of existing free ribosomes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...