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  • Electron microscopy  (46)
  • Springer  (46)
  • American Chemical Society
  • Oxford University Press
  • Annual Reviews
  • 2005-2009
  • 1990-1994
  • 1980-1984  (46)
  • 1980  (46)
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  • Springer  (46)
  • American Chemical Society
  • Oxford University Press
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  • 2005-2009
  • 1990-1994
  • 1980-1984  (46)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 30 (1980), S. 43-50 
    ISSN: 1432-0827
    Schlagwort(e): Osteogenesis ; In vitro ; Electron microscopy ; Mineralization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Chick limb mesenchymal cells differentiate into muscle, cartilage, fibrous, and bone tissue. Previous reports show that when stage 24 limb mesenchymal cells are cultured in vitro, chondrocytes, myocytes, fibrocytes, and osteoblasts can be identified on the basis of morphological and biochemical parameters. The study reported here demonstrates that phenotypic expression in culture seems to be dependent on the initial plating density, Scanning electron microscopic observations indicate that when stage 24 limb mesenchymal cells are initially seeded at high densities (5 × 106 cells per 35 mm culture dish), mounds of cells appear in culture. These mounds represent cartilage nodules composed of a fine fibrous matrix and chondrocytes, surrounded by a loose fibrous connective tissue matrix. Cultures initially plated at intermediate densities (2.0–2.5 × 106 cells/35 mm culture dish) produce a flattened layer of fibrocytes overlying a matrix of collagen fibers and calcium phosphate deposits as determined by electron-microprobe analysis; these observations are indicative of osteoblast expression. Cells seeded at this intermediate density appear larger and possess greater surface area than cells seeded at high density. It is suggested that conditions that permit such increased cell surface area coupled with a relative compaction due to cell crowding may provide conditions permissive for osteogenesis. Based on morphological criteria, it appears that chick limb mesenchymal cell osteogenesis in vitro is not associated with chondrogenesis but represents a separate route of phenotypic expression.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1432-0827
    Schlagwort(e): Rat ; Calvarium ; Electron microscopy ; Preosteoclasts ; Osteoclasts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary This is a study of the fine structure of cells of the 20-day fetal rat calvarium. Special attention is given to identifying and characterizing preosteoclasts. These cells are relatively common and located largely, but not exclusively, at the endocranial bone surface. The preosteoclasts are characterized by abundant mitochondria, an incomplete perinuclear Golgi apparatus, and variable-shaped dense granules. The dense granules are unique in appearance in that they contain an internal dense matrix surrounded by a clear halo. Most granules are circular in shape but some are elongate or tubular in form. Granules with identical appearance are observed in osteoclasts. The preosteoclasts are mononucleate, or occasionally binucleate. It is suggested that because preosteoclasts are morphologically distinctive and relatively abundant, it should be feasible to separate these cells from a heterogeneous cell isolate.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1432-0827
    Schlagwort(e): Decalcification ; Electron microscopy ; Bone matrix ; Bone glycoproteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary A solution of triethylammonium EDTA in 80% ethanol was evaluated as a demineralizing reagent for bone in comparison with aqueous solutions of EDTA. Biochemical analysis and acrylamide gel electrophoresis of extracts of finely powdered bovine bone showed that most of the macromolecular components of the organic matrix extractable in aqueous EDTA were retained when the triethylammonium EDTA reagent was used. Ultrastructural examination of chick tibias decalcified with the reagents showed a better preservation of cellular morphology, especially the membranous components, and more uniformly distributed ground substance, though slightly less in quantity, when the aqueous reagent was used. Use of the two reagents appears to be complementary, the alkylammonium reagent being more appropriate for use in studies of the organic matrix of bone, including immunohistochemical studies of bone glycoproteins. The aqueous reagent is more appropriate for use in studies of cellular ultrastructure.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 128 (1980), S. 179-189 
    ISSN: 1432-072X
    Schlagwort(e): Allomyces ; Zoospores ; Cell wall ; Chitin ; Gamma particle ; Encystment ; Electron microscopy ; Calcofluor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Structural changes during cell wall formation by populations of semisynchronously germinating zoospores were studied in the water mold Allomyces macrogynus. Fluorescence microscopy using Calcofluor white ST (which binds to β-1,4-linked glycans) demonstrated that Calcofluor-specific material was deposited around most cells between 2–10 min after the induction of encystment (beginning when a wall-less zoospore retracts its flagellum and rounds up). During the first 15 min of encystment there was a progressive increase in fluorescence intensity. Ultrastructural analysis of encysting cells showed that within 2–10 min after the induction of encystment small vesicles 35–70 nm diameter were present near the spore surface, and some were in the process of fusing with the plasma membrane. The fusion of vesicles with the zoospore membrane was concomitant with the appearance of electron-opaque fibrillar material outside the plasma membrane. Vesicles similar to those near the spore surface were found within the gamma (γ) particles of encysting cells. These particles had a crystalline inclusion within the electron-opaque matrix. During the period of initial cyst cell wall formation numerous vesicles appeared to arise at the crystal-matrix interface. Approximately 15–20 min was required for the cell wall to be formed. We suggest that the initial response of the zoospore to induction of encystment is the formation of a cell wall mediated by the fusion of cytoplasmic vesicles with the plasma membrane.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 126 (1980), S. 277-283 
    ISSN: 1432-072X
    Schlagwort(e): Bacteriophage ; Myxococcus ; λ ; Superooiled DNA ; Cross-linking ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract DNA was partially released from the heads of myxococcus phages and also coliphage λ and examined by electron microscopy by a modification of the Kleinschmidt technique, in which water was used as hypophase. DNA emerged from the heads in patterns suggestive of newly relaxed supercoils. The unreleased DNA appeared to occupy discrete regions in the head. Some closed circles were released from λ heads. When NaCl solution was used as hypophase, the DNA was observed either released from the tail or from the head, in the latter case, supercoiled regions were observed. When NH4OAc solution was used as hypophase, tightly wound structures were released from λ heads; these fields also contained supercoiled circles. The presence of constrained supercoiled domains in newly released phage DNA was confirmed by observing the effects of ethidium bromide on its conformation. Treatment of phage with nitrogen mustard, a bifunctional alkylating agent, preserved supercoiled domains, even when the phage were lysed over water as hypophase. Further experiments suggested that phage inactivation by nitrogen mustard is largely due to restraint of the supercoiled, native, tertiary structure and that DNA-protein cross-linking may be involved in this reaction. The implications of these findings for the conformation of phage DNA in vivo are discussed and a new model for the winding of DNA in phage heads is proposed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 1432-072X
    Schlagwort(e): Immunoferritin labeling ; Electron microscopy ; Membrane vesicles ; Nitrate reductase ; Bacillus licheniformis ; Klebsiella aerogenes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The indirect immunoferritin labeling method was used to localize the membrane-bound respiratory nitrate reductase in membrane vesicles and protoplasts or spheroplasts of Bacillus licheniformis and Klebsiella aerogenes, respectively. For a comparison of the labeling of the various vesicle preparations, which differed not only in size but also in the percentage of inside-out orientation, a quantification of the results was needed to circumvent the problem of non-specifically bound ferritin. From the results the sidedness of the nitrate reductase in the cytoplasmic membrane of the abovementioned bacteria was determined as being cytoplasmic in B. licheniformis and as transmembranous in K. aerogenes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 128 (1980), S. 12-18 
    ISSN: 1432-072X
    Schlagwort(e): Moraxella glucidolytica ; Electron microscopy ; Lipopolysaccharide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A cellular (LPS I) and extracellular (LPS II) lipopolysaccharide were isolated from Moraxella glucidolytica cells grown on ethanol and from the culture fluid, respectively. Both LPS were toxic when injected to mice and chick embryos. These LPS contained glucose, galactose, glucosamine, galactosamine, 2-keto-3-deoxyoctonate and lipids. By permethylation studies, glucose was found to be linked (1→6) and (1→3) in LPS I and only (1→6) in LPS II. Galactose was the terminal non-reducing sugar. Branching occurred at positions 3 and 4 of galactose residues. LPS I was rich in α- and β-hydroxylauric and α-hydroxymyristic acids and LPS II contained mainly stearic and α-hydroxymyristic acids. LPS I was detoxified by mild acid and alkaline treatments. It was also dissociated by sodium deoxycholate and chromatographed on Sephadex G-75. The main fraction was reassociated by removing the surfactant by dialysis. The morphology of LPS I and LPS II was examined by electron microscopy. LPS I (original and reassociated fractions) consisted exclusively of ribbons while LPS II contained ribbons and vesicles.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 126 (1980), S. 87-95 
    ISSN: 1432-072X
    Schlagwort(e): Ascodichaena ; Beech bark ; Electron microscopy ; Host-fungus relationship
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Ascodichaena rugosa Butin is a corkinhabiting fungus, found frequently on the bark of Fagus sylvatica L. The hyphae of the fungus are distributed solely in the phellem cells, stopping their growth in the last-formed cork cell layer. The cell to cell invasion is effected by penetration hyphae, causing no extensive dissolution of the cork wall. Electron microscopical observations revealed fine structural details of the fruit bodies and of the intracellular hyphae. Of special interest were the finger-like hyaline hyphae in the last-formed layer of cork cells, which are interpreted as haustoria on the basis of the fine structure both of hyphae and host cells. This situation is considered as reflecting a parasitic relationship of Ascodichaena to beech bark. The activity of the fungus led also to the increased production of cork cells, perhaps related to the nutrient supply of the fungus.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 206 (1980), S. 55-63 
    ISSN: 1432-0878
    Schlagwort(e): Phagocytosis ; Spermatozoa ; Ovum ; Fertilization ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Spermatozoa with intact acrosomes, as well as those coming into contact with the ovum at a smaller angle, and morphologically abnormal spermatozoa reach the plasma membrane of the ovum via an extensively dissolved zone of the inner layer of the vitelline membrane. This zone is assumed to be formed by overlapping of two or more tunnels formed by spermatozoa that had previously come into contact with the ovum. When a spermatozoon comes into contact with the plasma membrane of the ovum, many cytoplasmic processes extend outwards and cover it. Thereafter, the plasma membranes of the processes fuse, thereby phagocytizing the spermatozoon. It is assumed that the phagocytized spermatozoa cannot undergo transformation into male pronuclei and that they degenerate soon after phagocytosis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 206 (1980), S. 225-232 
    ISSN: 1432-0878
    Schlagwort(e): Compound eye ; Photoreceptor membrane ; Electron microscopy ; Calcium-induced changes ; Artefacts ; Diptera
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary When the compound eyes of the fly Lucilia are fixed for electron microscopy with glutaraldehyde in common buffer solutions, artefactual whorls are liable to be formed from the photoreceptor microvilli. The whorls result from two factors: (i) a prolonged time interval prior to osmication, such as the “overnight” primary fixation or wash at 4° C commonly used in studies of compound eyes; (ii) as little as 1–2 mM Ca++ in the primary fixative and wash solutions. Osmication after short (1 h) glutaraldehyde fixation at 4° C, or omission of Ca++ and addition of 2 mM EGTA, prevent whorl-formation. In the tipulid fly Ptilogyna, similar artefacts are produced, but are confined to the distal zone of the microvilli that sheds during turnover.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 211 (1980), S. 83-93 
    ISSN: 1432-0878
    Schlagwort(e): Epithelium ; Cloaca ; Electron microscopy ; Hen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The epithela of the three divisions (coprodaeum, urodaeum, proctodaeum) of the cloaca of the hen, and of the excretory ducts (colon, ureter, vagina) which join the divisions, are described using light microscopy, and scanning and transmission electron microscopy. Each region of the cloaca has its typical epithelium. Special attention is focussed in this study on the boundaries between the different epithelia. The coprodaeal epithelium does not differ considerably from that of the colon; a transitional zone is not visible. Distinct border zones, however, are observed between the other regions (ureter — urodaeum; vagina — urodaeum and proctodaeum; urodaeum-proctodaeum; proctodaeum — cutis). Although the vaginal opening is generally thought to lie in the urodaeum, our investigations show that at the vaginal opening into the cloaca the ciliated epithelium changes, on one border to a secretory epithelium characteristic of the urodaeum and on the other border to that characteristic of the proctodaeum. These observations are discussed in relation to functional aspects.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 211 (1980), S. 171-174 
    ISSN: 1432-0878
    Schlagwort(e): Pancreatic D cell ; Neural control ; Vagotomy ; Electron microscopy ; Fowl
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In an attempt to determine the neural control of pancreatic D cells, the pancreatic islets of the domestic fowl were examined electron microscopically from 1 to 28 days after abdominal vagotomy. Exocytotic release of many secretory granules from D cells occurred one day after vagotomy. Rough endoplasmic reticulum developed and formed an arrangement of concentric whorls in the cytoplasm of D cells after axotomy. The altered D cells were also characterized by the occurrence of many peculiar dense bodies in the apical cytoplasm at all time periods studied. These bodies varied in shape and size, containing several round vesicles. The D cells were extensively depleted of granules after the longer time periods following vagotomy. The present results provide new morphological evidence for the vagus-nerve control of D cells, which may regulate the activity of islet cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 211 (1980), S. 191-206 
    ISSN: 1432-0878
    Schlagwort(e): Hypothalamus ; Transplants ; Vasopressin ; Median eminence ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Blocks of anterior hypothalamus were transplanted from 19 day-old fetuses of Wistar/Lewis rats into the third ventricle of adult male Brattleboro rats. Physiological changes in graft recipients and in sham-operated animals were monitored daily. Twenty days after surgery, the graft recipients and shamoperated animals were killed and their brains examined by correlative scanning and transmission electron microscopy. Host animals that exhibited both decreased polydipsia and increased urine concentration were found to have viable grafts within the third ventricle. The observed physiological changes suggested that synthesis and release of vasopressin occurred in the transplanted neurons. Grafts were well vascularized by vessels arising from the host hypothalamus. Neurons, with perikarya ranging from 8 to 30 μm in diameter, glial cells, and neurites were located throughout the transplants. A neurohemal contact zone, similar to that normally seen in the median eminence, could not be demonstrated in the grafts. The absence of complete glial and ependymal barriers indicates a relatively close association between cells in the transplants and the cerebrospinal fluid. A large increase in supraependymal neurons and their processes, including an eruption of neurons through the floor of the third ventricle in one animal, was observed in graft recipients but not in shamoperated animals.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 206 (1980), S. 303-318 
    ISSN: 1432-0878
    Schlagwort(e): Area postrema, rat ; Ependyma ; Cyst ; Circumventricular organs ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Peculiar cells forming cysts were observed in the area postrema and sometimes also in the choroid plexus and the tela chorioidea near the area postrema, and were studied in detail by electron microscopy. The cytological features of the cyst cell and its junctional relationship to neighboring cells imply that cyst cells are derived from ependymal and choroid epithelial cells. The cyst cells usually contact directly the perivascular spaces of postremal, choroidal or pial capillaries, where the cytoplasm is often considerably attenuated. The cystic lumen is commonly filled with a flocculent material. The limiting membrane of the cystic lumen, which frequently bears cilia and microvilli, has the same thickness as the surface cell membrane. In many cases, the cyst is surrounded by the cytoplasm of a single cell. In some cases, however, two cells participate in the formation of the cyst, although one is only a slender process and joined by a zonula occludens with the main cyst cell. Horseradish peroxidase (HRP) injected into the cerebrospinal fluid (CSF) space failed to enter the cystic lumen. A possible significance of the cyst in relation to the CSF and blood circulation was considered.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 210 (1980), S. 447-459 
    ISSN: 1432-0878
    Schlagwort(e): Lipid ; Kidney tubules, proximal ; Autoradiography ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Lipid metabolism in the cells of the renal proximal convoluted tubules (PCT) was investigated in healthy fowls and in fowls with the Fatty Liver and Kidney Syndrome (FLKS). The tissue was fixed at 10–25 min intervals after intravenous injection of 3H-oleic acid. The distribution of autoradiographic grains was analysed by the “circle method”. In normal cells most of the silver grains were associated with the cytoplasmic organelles. Lipid droplets and Golgi elements had the highest specific activity relative to the nuclear activity, which was little above background level. Lysosome-like bodies and mitochondria had lower values. In the cells of the FLKS-affected birds a large proportion of the grains was located over the lipid droplets, which are abundant in this condition. The specific activity of the cytoplasmic organelles was barely 2-fold higher than the nuclear activity. The results suggest that there is a diminished incorporation of esterified fatty acids by the organelles of these cells and that the excess is transferred to the lipid droplets. The identity of low electron density particles observed in the PCT cells of severely affected birds is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 211 (1980), S. 331-343 
    ISSN: 1432-0878
    Schlagwort(e): Gut hormones ; Endocrine cells ; Electron microscopy ; Immunocytochemistry ; Peptidergic innervation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Histological, cytochemical and immunocytochemical methods were used in light and electron microscopical studies to demonstrate the presence of a neuroendocrine system in the gut of the urodele, Salamandra salamandra. Cytochemical stains capable of detecting peptide-producing endocrine cells demonstrate cells reacting with Masson's silver (argentaffin) method, Grimelius' argyrophil silver method, masked metachromasia method and the lead haematoxylin stain. Using antisera raised to a variety of mammalian gut peptides, cells containing bombesin-, gastrin-, somatostatin-, substance P- and glucagon-like immunoreactivity were identified; vasoactive intestinal polypeptide- and substance P-like immunoreactivities were found in nerve fibres in the submucous and myenteric plexus. No immunoreactivity was detected for motilin, gastric inhibitory polypeptide, cholecystokinin or secretin. The ultrastructure of the immunoreactive cells and nerves was revealed by the semithin/thin method. All the cells identified contained numerous electrondense secretory granules, which varied in their chracteristic morphological structure from one cell type to another. The evidence collected in this study indicates that a complex neuroendocrine system regulating gut function is present in this amphibian and may have developed prior to the emergence of the phylum.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 210 (1980), S. 269-282 
    ISSN: 1432-0878
    Schlagwort(e): Monoaminergic neurons ; Retina ; Amacrine cells ; Neurotoxins ; Mudpuppy, Necturus maculosus ; Neurotransmitters ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The mudpuppy retina was investigated with the histofluorescence method of Falck and Hillarp in normal animals and in animals injected intraocularly with α-methylnoradrenaline, 5,6-dihydroxytryptamine, or a combination of the two drugs. Catecholaminergic amacrine cells were found to form a thin layer of terminals at the border between the inner nuclear and the inner plexiform layers. Catecholaminergic interplexiform cells were not found. Indoleamine-accumulating amacrine cells were also observed. They are fifteen to twenty times more numerous than the catecholaminergic cells, and their terminals occur diffusely throughout the inner plexiform layer. In a number of eyes the majority of the indoleamine-accumulating terminals were eliminated with intraocular injections of the neurotoxin, 5,7-dihydroxytryptamine, but the reproducibility of this effect was not consistent. Intravitreal injections of 5,6-dihydroxytryptamine were used to label both types of neurons for electron microscopy. They were found to make conventional type synapses on amacrine cells and, less frequently, on bipolar cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 210 (1980), S. 353-357 
    ISSN: 1432-0878
    Schlagwort(e): Merkel cells (reptiles) ; Epidermis ; Lizard ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Examination of the labial epidermis of the lizard Lacerta sicula revealed cells displaying all features of Merkel cells. These cells are located in the stratum basale of epidermal pegs and are arranged in clusters.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 211 (1980), S. 293-301 
    ISSN: 1432-0878
    Schlagwort(e): Paneth cell ; Hibernation ; Intestine ; Hypothermia ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of Paneth cells from jejuno-ileal segments of the small intestine of the ground squirrel, S. lateralis, was examined under normal euthermic conditions and during the profoundly depressed metabolic conditions of natural hibernation. Paneth cells obtained from hibernating animals gave evidence of markedly reduced activity when compared to Paneth cells from euthermic animals. In hibernating animals, the nuclei were smaller, with less prominent nucleoli and with an increased proportion of heterochromatin. In hibernating animals, the rough endoplasmic reticulum was fragmentary and poorly organized, in contrast to the typical arrangement of concentric lamellae seen in euthermic animals. Although the total number of ribosomes was decreased in hibernating animals, there were proportionally more free ribosomes than in euthermic animals. Paneth cells from hibernating animals also contained a greater number of apical secretory granules which were smaller and more variable in electron density than granules from control animals. These ultrastructural features indicate that during hibernation the Paneth cell is relatively quiescent.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 207 (1980), S. 511-517 
    ISSN: 1432-0878
    Schlagwort(e): Female hamster ; Harderian gland ; Testosterone ; Tubular clusters ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Distinct differences occur in the pigmentation and ultrastructural features of the Harderian glands in male and female hamsters. The results of a study on the effect of testosterone on the fine structure of the female Harderian glands are presented here. Glands from three groups of hamsters were examined at intervals up to 49 days: (1) testosterone injected, receiving 2mg testosterone propionate in 0.1 ml sesame oil per day; (2) sham-injected, receiving 0.1 ml sesame oil per day; (3) untreated controls. Testosterone injections caused a reduction in the number of dark-brown pigment granules in the acinar cells starting on the 6th day, whereas clusters of tubules, typical of adult male glands, appeared on the 4th day and increased in number thereafter. Lamellar structures, normally present in the female gland, decreased in testosterone treated specimens. These changes reversed after cessation of testosterone treatment. It is concluded that exogenous testosterone administered to female hamsters modifies the pigmentation and ultrastructure of their Harderian glands towards the male type and that this is a reversable phenomenon. There also appears to be an inverse relationship between the presence of tubular clusters in the acinar cells, and the degree of pigmentation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 208 (1980), S. 171-181 
    ISSN: 1432-0878
    Schlagwort(e): Microtubules ; Dendritic spine apparatus ; Synapse ; Development ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Using techniques for enhanced microtubular preservation, including albumin pretreatment (Gray, 1975), occipital cortex of rats was studied electron microscopically at various ages of development. A close structural relationship was seen between microtubules, sacs of SER and the postsynaptic “thickening” in primordial spines and with the dense “plate” material of spine apparatuses. Stereoscopic preparations in addition show a more complicated substructure than previously described for the “plate”. Microtubules may contribute to the formation of the “plate” of the spine apparatus which in turn is associated with the postsynaptic “thickening” of the mature spine. Possible functional correlates are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 209 (1980), S. 131-135 
    ISSN: 1432-0878
    Schlagwort(e): Skeletal muscle ; Bupivacaine ; Degeneration ; Satellite cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Rat lumbrical muscles were incubated in a concentration of 10-2 M bupivacaine for 5 or 15 min and examined after further incubation in the absence of the drug for periods totalling 1, 2, and 3h. Electron microscopy showed that muscle fibers and their component organelles and myonuclei underwent a series of irreversible degenerative changes. However, satellite cells retained their normal morphology under similar conditions. It is concluded that satellite cells are responsible for the rapid regeneration of muscles that follows degeneration induced by bupivacaine. The role of satellite cells in muscle regeneration is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 207 (1980), S. 135-142 
    ISSN: 1432-0878
    Schlagwort(e): Caudal neurosecretory system ; Poeciliidae ; Electron microscopy ; Salinity changes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The urophysis or neurohemal contact site of the caudal neurosecretory system of Mollienesia sphenops, the black molly, was studied in animals adapted to an artificial seawater environment. This species of fish was chosen for these studies because of its known ability to osmoregulate and its adaptability to the laboratory aquarium. The urophysis of freshwater acclimated mollys contained an abundance of neurosecretory granules. However, in fish subjected to a seawater environment for one week the number of neurosecretory granules was significantly decreased. In addition, there was an increase in blood cell infiltration of the urophysis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 24
    ISSN: 1432-0878
    Schlagwort(e): Juxtaglomerular apparatus ; Sympathetic innervation ; Renin-angiotensin system ; Electron microscopy ; Fluorescence microscopy ; Tupaia belangeri ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary It has previously been reported that the primitive primate Tupaia belangeri develops a renal failure when exposed to psychosocial stress. In order to learn if this high susceptibility to stress of the Tupaia kidney can be correlated with morphological and functional parameters of the Juxtaglomerular apparatus (JGA) and the renin-angiotensin system, comparative experiments were performed on Tupaia and rat. Our results reveal an outstandingly high potency of the JGA and the renin-angiotensin system in Tupaia as evident from the following findings: The Tupaia JGA contains a great number of epithelioid cells abounding in renin granules (electron microscopy). The renin content of the Tupaia kidney is considerably higher than in the rat (radio-immunoassay). The sympathetic innervation of the kidney and especially of the JGA is abundant in Tupaia (fluorescence and electron microscopy). Catecholamine contents of the kidney and other organs are significantly higher in Tupaia than in rats (spectrophotofluorometry). Our results support the previously developed concept of a potent intrarenal neuroendocrine interaction at the JGA level favouring, under certain conditions of social stress, the development of acute renal failure in Tupaia belangeri.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 212 (1980), S. 465-474 
    ISSN: 1432-0878
    Schlagwort(e): Postcapillary venules ; Calf ; Lymph nodes ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The structure of the postcapillary “high endothelial venules” (HEV) of lymph nodes in calves was studied light and electron microscopically. These venules were detected light microscopically in the paracortical zone by their high cuboidal endothelium, a distinct basal lamina, the migration of lymphocytes through the vessel wall, and the dominance of lymphoid cells in the lumen, often completely obliterating the latter. Ultrastructurally, the endothelial cells (HEC) of the HEV were characterized by a prominent Golgi complex including many small vesicles, a few lysosome-like bodies, and a specific association between mitochondria and rough endoplasmic reticulum (MER). The HEC are connected by desmosomes, whereas the intimate contact points between migrating lymphocytes and endothelial cells could not be classified according to the well-defined junctional types. Lymphocyte migration occurred predominantly intercellularly, i.e., between endothelial cells. Although the overall appearance of the described vessel type in bovines bears resemblance to HEV in other investigated species, several differences occur that most probably are related to species variation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Parasitology research 62 (1980), S. 31-38 
    ISSN: 1432-1955
    Schlagwort(e): Haemohormidium cotti ; Light microscopy ; Electron microscopy ; Taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Haemohormidium cotti, an organism of uncertain status, is redescribed from one of its type hosts, the marine fish,Cottus bubalis. The parasite occurs as irregularly round, oval, or elongate, intraerythrocytic bodies within blood and tissue preparations. Electron micrographs show features which suggest thatH. cotti may, as previously suspected, belong with the Piroplasmasida but no firm evidence of this is established. Possible division stages are identified in both light and electron micrographs. The taxonomic position ofHaemohormidium is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    ISSN: 1432-1955
    Schlagwort(e): Babesia microti ; Electron microscopy ; Ticks ; Ixodes ricinus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 205 (1980), S. 187-198 
    ISSN: 1432-0878
    Schlagwort(e): Pancreatic polypeptide (PP) ; Glucagon ; Pancreatic islet ; Xiphophorus helleri ; Immunohistochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé L'étude immunohistochimique de l'îlot pancréatique du poisson téléostéen Xiphophorus helleri, à l'aide de sérums anti-polypeptide pancréatique (PP) et anti-glucagon a permis de montrer que deux populations cellulaires distinctes sont responsables de la sécrétion de ces hormones. L'observation comparée de coupes sériées, ultrafines et semifines, traitées par la technique immunohistochimique, a démontré que les cellules à PP correspondent aux cellules qui avaient été précédemment définies, dans cette espèce, comme “cellules A2 à grains ronds” et que les cellules sécrétrices de glucagon sont les “cellules A2 à grains cristallins”. L'hypothèse de l'existence de deux catégories de cellules à glucagon chez les téléostéens est abandonnée.
    Notizen: Summary Correlative immunohistochemical and electron microscopical studies on the pancreatic islet of the teleost fish Xiphophorus helleri using antibodies to pancreatic polypeptide (PP) and glucagon show that separate cell types are responsible for the production of these peptides. The PP-cells correspond to the previously described “A2-cells with round granules”, while the “A2-cells with crystalline granules” are the true glucagon cells. An earlier suggestion that there are two types of glucagon cells in teleost islets is therefore withdrawn.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 206 (1980), S. 395-401 
    ISSN: 1432-0878
    Schlagwort(e): Dragonfly visual system ; Lamina ganglionaris ; Monopolar cells ; Optic neuropile ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Five monopolar cells and two long visual fibres are a consistent component of the lamina cartridge of the ventral half of the eye of the dragonfly Sympetrum rubicundulum. They communicate with the chiasm via a cartridge axon bundle comprising a minimum of ten fibres. The arrangement of these elements is documented with respect to the ommatidial photoreceptor axon bundle innervating them. These relationships are described both within the lamina cortex and in the cross-section of the underlying cartridge.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 207 (1980), S. 233-239 
    ISSN: 1432-0878
    Schlagwort(e): Kidney ; Triturus cristatus carnifex ; Erythropoiesis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Specimens of Triturus cristatus carnifex (Laurenti), raised in 3.2 g/l solution of sodium lactate, presented hypertrophy of “lactate sensitive cells” (LSC) clustered at the vascular pole of each renal corpuscle. As seen under both the light and electron microscopes, these are specialized cells of the Bowman's capsule located at the junction between its visceral and parietal layers. The structure formed by the cells, heretofore unknown, is topographically associated with the juxtaglomerular apparatus. As lactate stimulates erythropoiesis even in normal oxygenated specimens and hypoxia induces hypertrophy of LSC in newts, it is hypothesized that the LSC are the site of erythropoietin (ESF) synthesis. A scheme of ESF biogenesis in newts, integrating the above principles, concludes the paper.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 207 (1980), S. 287-306 
    ISSN: 1432-0878
    Schlagwort(e): Fetal human thymus ; Epithelial cells ; Development and differentiation ; Mesenchymal reticulum cells ; T lymphocytes ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ontogenetic differentiation of the human thymus was investigated in 50 embryos by means of light and electron microscopic methods in an attempt to clarify the morphogenesis of the complicated microecology of thymic tissue. At the 8th gestational week (g.w.), the primordium of the thymus contains almost exclusively undifferentiated epithelial cells. At the 10th g.w., the epithelial cells in the central part are spindle-shaped. During the subsequent weeks the cortical region of the thymus becomes separated into lobes by mesenchymal septa containing hemopoietic precursor cells and large electronlucent cells with irregularly shaped nuclei. The latter cells are also found in the deeper presumptive medullary regions of the thymus; they differentiate into interdigitating reticulum cells (IDC). The permeation of the medulla of the thymus by non-epithelial IDC occurs concurrently with the formation of cortical and medullary epithelial cells. Between the 12th and 14th g.w. the cortical and medullary differentiation is completed. At this time-stage cortical small lymphocytes differ in morphological shape from medullary lymphocytes, the latter acquiring the appearance of immunocompetent T cells and establishing intimate contact with the IDC. These findings indicate that the thymic cortex and medulla contain different epithelial cells. In addition, the thymic medulla displays cells characterized by the morphology of typical interdigitating reticulum cells of peripheral lymphoid tissue. The structural pattern of the thymus is correlated to morphologically differing lymphoid cell populations in the cortical and medullary regions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 32
    ISSN: 1432-0878
    Schlagwort(e): Supraependymal cells ; Macrophages ; Electron microscopy ; Lateral ventricles ; Amphibian brain
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Transmission and scanning electron microscopy of the lateral ventricles of the toad brain revealed the presence of supraependymal cells that have the features of macrophages. Based solely on their surface morphology three different cell forms could be identified. The most frequently observed cells are flat and multipolar, and have a smooth or ruffled surface. The second type is spherical with a ruffled surface and occurs either singly, in which case it lacks processes, or in clusters from which processes radiate. The third type has surface blebs and numerous thin, smooth processes. However, when specimens that had been examined in the scanning electron microscope are viewed in the transmission electron microscope, all cells appear to belong to a single cell type. All cells viewed closely resemble macrophages in that they contain nuclei with clumped chromaffin, single cisternae of rough endoplasmic reticulum, numerous dense bodies, and many Golgi complexes. In addition, when horseradish peroxidase (HRP) was perfused into the ventricles, reaction product was found a short time thereafter within cytoplasmic vacuoles, and after a longer period within dense bodies. Because of their ultrastructural resemblance to macrophages and their capacity to ingest HRP, we suggest that these cells function as phagocytes and, as such, act to remove foreign materials from the cerebrospinal fluid.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 207 (1980), S. 429-448 
    ISSN: 1432-0878
    Schlagwort(e): Islet of Langerhans ; Aging ; Insulin-secreting cells ; Organ culture ; Electron microscopy ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The B-cells of the endocrine pancreas constitute an adequate model for in vitro study of the aging process in highly differentiated cells. In the present study, collagenase-isolated islets of Langerhans from young and senescent rats were cultured up to 28 days. The response of the B-cells to the stimulatory conditions of the culture medium involved the nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, and secretory granules. Correlated data from light microscopy, electron microscopy, and insulin radioimmunoassay show that the differentiation and function of senescent B-cells are maintained in culture, as it has been proven for the B-cells of younger animals. On the other hand, signs of cytological deficiency not directly concerned with the specific function of B-cells were observed: abnormal mitochondria and lysosomes are more numerous in the senescent B-cells. The proliferative capacity of the B-cells of aged rats is reduced.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 207 (1980), S. 449-461 
    ISSN: 1432-0878
    Schlagwort(e): Rhynchosciara angelae ; Salivary gland ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The structure of the salivary gland of the dipteran insect Rhynchosciara angelae in a defined stage of the larval development, characterized by the synthesis and storage of secretion product, is described. Observations were made with both Nomarski optics and electron microscopy. Filiform projections extending into the lumen of the gland were observed in the apical portion of the cells. At the basal region junctions, characterized as hemidesmosomes, were observed between the membrane of the cell and the basal lamina. The plasma membrane presents numerous infoldings into the cell increasing considerably the surface area at this region. Throughout the cytoplasm of the gland cells numerous mitochondria, Golgi complexes, microtubules, profiles of endoplasmic reticulum, secretion granules and glycogen granules were observed. Carbohydrates were detected on ultrathin sections by using the periodic acid-silver methenamine and the periodic acid-thiosemicarbazide-silver proteinate techniques.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 208 (1980), S. 143-164 
    ISSN: 1432-0878
    Schlagwort(e): Locomotory muscle ; Fibre types ; Antarctic fish (Notothenia rossii) ; Histochemistry ; Electron microscopy ; Energy metabolism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The metabolic and structural differentiation of locomotory muscles of Notothenia rossii has been investigated. In this species sustained locomotion is achieved by sculling with enlarged pectoral fins (labriform locomotion), whilst the segmental myotomal muscle is reserved for burst activity. Red, white and subepidermal fibres can be distinguished in the trunk by histochemical and ultrastructural criteria. The main pectoral muscle (m. adductor profundus) consists entirely of red fibres. These three main fibres types show differences in histochemical staining profiles, capillarization, myofibril shape and packing, and lipid and mitochondrial content. The fractional volume of mitochondria amounts to 38% for pectoral, 30% for red myotomal and 1.9% for white myotomal fibres. Enzyme activities of red pectoral muscle are consistent with a higher potential for aerobic glucose and fatty acid oxidation than for the red myotomal fibres. Mg2+ Ca2+ -myofibrillar ATPase activities are similar for red pectoral and myotomal muscles and approximately half of those white fibres. Specialisations of N. rossii muscles associated with labriform swimming and locomotion at Antarctic temperatures are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 208 (1980), S. 207-228 
    ISSN: 1432-0878
    Schlagwort(e): Hind stomach ; Fundic glands ; Electron microscopy ; Histochemistry ; Endocrine cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The epithelium of the fundic region mucosa of the hind stomach in the Llama guanacoe has been studied using morphological and histochemical methods. Morphology suggests that solute and water absorption may occur in the epithelium of the surface and of the foveolae, although this absorption can not be estimated because of the extensive secretion of the gastric glands. The same cells of the surface and foveolar epithelium show numerous secretory granules. The glands reveal neck cells, chief cells, a large number of oxyntic cells, four types of endocrine cells (A-like, ECL, D and EC), brush cells and wandering cells. PAS and Alcian blue reactions for light microscopy suggest a secretion of neutral and acidic mucosubstances in the surface and foveolar epithelium, of neutral mucosubstances only in the neck cells. Periodic acid-thiocarbohydrazide silver proteinate (PA-TCH-SP) reaction for electron microscopy confirms the presence of neutral mucosubstances within the secretory granules of the surface, foveolar and neck epithelial cells. In all these cells, the reaction product is also evident within sacculi and vesicles of the maturing surface of the Golgi apparatus. A positive PA-TCH-SP reaction also occurs on the membrane (and not on the contents) of the Golgi apparatus (maturing surface) and of the secretory granules of the chief cells as well as on the membrane of the Golgi apparatus and of apical vesicles and tubules of the oxyntic cells. In addition, silver granules slightly enhance the electron density of the contents of the secretory granules in the endocrine cells. Morphological and histochemical findings are discussed and compared with results described by others for monogastric mammals.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 208 (1980), S. 371-387 
    ISSN: 1432-0878
    Schlagwort(e): Lobula complex ; Visual interneurons ; Ultrastructure ; Cobalt-impregnations ; Electron microscopy ; Diptera (Calliphora erythrocephala)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The synaptic organization of three classes of cobalt-filled and silver-intensified visual interneurons in the lobula complex of the blowfly Calliphora (Col A cells, horizontal cells and vertical cells) was studied electron microscopically. The Col A cells are regularly spaced, columnar, small field neurons of the lobula, which constitute a plexus of arborizations at the posterior surface of the neuropil and the axons of which terminate in the ventrolateral protocerebrum. They show postsynaptic specializations in the distal layer of their lobula-arborizations and additional presynaptic sites in a more proximal layer; their axon terminals are presynaptic to large descending neurons projecting into the thoracic ganglion. The horizontal and vertical cells are giant tangential neurons, the arborizations of which cover the anterior and posterior surface of the lobula plate, respectively, and which terminate in the perioesophageal region of the protocerebrum. Both classes of these giant neurons were found to be postsynaptic in the lobula plate and pre- and postsynaptic at their axon terminals and axon collaterals. The significance of these findings with respect to the functional properties of the neurons investigated is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 209 (1980), S. 11-28 
    ISSN: 1432-0878
    Schlagwort(e): Epiphysis cerebri ; Parapineal organ ; Fluorescence histochemistry ; Electron microscopy ; Gasterosteus aculeatus L ; Teleostei
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The pineal complex of the three-spined stickleback (Gasterosteus aculeatus L.) was investigated by light and electron microscopy, as well as fluorescence histochemistry for demonstration of catecholamines and indolamines. The pineal complex of the stickleback consists of a pineal organ and a small parapineal organ situated on the left side of the pineal stalk. The pineal organ, including the entire stalk, is comprised mainly of ependymal-type interstitial cells and photoreceptor cells with well-developed outer segments. Both unmyelinated and myelinated nerve fibres are present in the pineal organ. Nerve tracts from the stalk enter the habenular and posterior commissures. A small bundle of nerve fibres connects the parapineal organ and the left habenular body. The presence of indolamines (5-HTP, 5-HT) was demonstrated in cell bodies of both the pineal body and the pineal stalk, and catecholaminergic nerve fibres surround the pineal complex.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 39
    ISSN: 1432-0878
    Schlagwort(e): Visceral yolk sac ; Lipid droplets ; Malachite green-glutaraldehyde fixative ; Rat embryo ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of the visceral yolk sac (VYS) of the rat embryo at day 9.5 of gestation was examined after fixation with either Karnovsky's glutaraldehyde-paraformaldehyde solution or malachite green-containing glutaraldehyde (MGA) solution. Fixation with MGA retained homogeneously electron-dense droplets in the cytoplasm and the nucleus of endodermal cells, both of which were lost in the specimens prepared by Karnovsky's fixation method. The cytoplasmic MGA-positive droplets were frequently associated with other cytoplasmic organelles such as rough endoplasmic reticulum, mitochondria and membrane-delineated inclusion bodies, but these cytoplasmic organelles never incorporated MGA-positive materials, whereas Golgi apparatus contained intracisternal MGA-positive droplets. Extracellular MGA-positive droplets were also encountered at the apical surface of endodermal cells and in the intercellular space between endodermal cells and the underlying mesodermal cells. These MGA-positive droplets were considered to be lipid in nature, and their origin in the endodermal cells of VYS is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 209 (1980), S. 225-238 
    ISSN: 1432-0878
    Schlagwort(e): Tanycytes ; Median eminence ; Electron microscopy ; Rat ; Serum LH
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The transport of hormones from the cerebrospinal fluid to the adenohypophysis by the tanycytes of the median eminence was examined in male rats. Electron microscopy revealed that all ependymal cells including the tanycytes disappear or degenerate in rats subjected to electric cauterization of the ependymal layer lining the third ventricle. However, the granular axons in the palisade layer of the median eminence remain intact. In rats subjected to electric lesion, no significant change was found in either the serum-LH level or in the weight of the adenohypophysis, testes, adrenal and thyroid glands. It is concluded that the tanycytes do not participate in the hypothalamic regulation of hypophysial function.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 209 (1980), S. 271-277 
    ISSN: 1432-0878
    Schlagwort(e): Intranuclear microtubules ; Chick embryo fibroblasts ; Frog Virus 3 ; Electron microscopy ; Tubulin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Intranuclear microtubules appear in chick embryo fibroblasts upon infection with Frog Virus 3 (FV 3). Both the diameter and the annular shape of the microtubule profiles, established from electron microscopic observations using a goniometer, suggest that they are identical to naturally occurring cytoplasmic microtubules. Furthermore, the use of vinblastine allowed demonstration of the tubulin composition of the intranuclear microtubules.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 209 (1980), S. 279-294 
    ISSN: 1432-0878
    Schlagwort(e): Germinal center reaction ; Dendritic reticulum cell ; Rabbit spleen ; Enzyme histochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary To obtain more information concerning the origin of dendritic reticulum cells, the development of germinal centers in the spleens of rabbits was investigated by conventional light microscopy, enzyme histochemistry, and electron microscopy. Washed sheep erythrocytes were used as antigen. Splenic tissue was examined on the 13th, 18th, 21st, 27th and 48th day after antigen administration. Electron microscopic investigations revealed transitional forms between typical fibroblastic reticulum cells, which formed the framework of the entire splenic white pulp, and typical dendritic reticulum cells. During this transformation, the enzyme histochemical pattern of alkaline phosphatase disappeared and a positive alpha-naphthyl acetate esterase reaction appeared in the transformed cells. On the basis of these findings, it is highly likely that dendritic reticulum cells develop through transformation of fibroblastic reticulum cells during the development of germinal centers in rabbit spleens. The characteristic folding of the surface membrane of dendritic reticulum cells is probably caused by the conspicuous increase in size of the Golgi apparatus, the detachment of vesicles, and the uptake of such vesicles by the cell membrane observed electron microscopically during the cellular transformation. Receptors that are of significance in antigen trapping might reach the cell surface in this manner, i.e., with the Golgi vesicles.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 211 (1980), S. 95-103 
    ISSN: 1432-0878
    Schlagwort(e): Synapse ; Synaptogenesis ; Cell culture ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In cell cultures of the rat cerebellum, electron-dense material has been found occasionally between adjacent cells. More often than not, presynaptic elements on one side of the dense material faced either neuronal or nonneuronal cells on the other side. The 20 nm thick material was stained either with the osmium-uranyl-lead (OsUL) procedure or with the ethanolic phosphotungstic acid (E-PTA) procedure. To determine the source of the dense material, various compounds were added to cultures at 7 days in vitro. Only a crude nuclear fraction was able to duplicate the appearance of the dense material associated with the apparent presynaptic elements. It was concluded that apparent presynaptic elements were associated with the polybasic dense material and that this type of association may duplicate an interaction in the normal development of synaptic contacts.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 212 (1980), S. 395-413 
    ISSN: 1432-0878
    Schlagwort(e): Kidney ; Distal tubule ; Collecting duct ; Electron microscopy ; Thin sections ; Freeze fracturing ; Tight junctions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Quantitative aspects of tight junction morphology were systematically studied in the cortical and outer medullary segments of the distal urinary tubules of rat, hamster, rabbit, cat, dog and the primitve primate Tupaia belangeri. Only minor differences in junctional architecture were found between straight and convoluted portions of the distal tubule. In contrast, the collecting duct in cortex and outer medulla, in all species, exhibits the most elaborate tight junctions observed along the uriniferous tubule. The present and previous findings from this laboratory indicate that increasing “tightness” of the junctional complexes is apparent along the course of the nephron in all species studied. The proposed relationship between quantitative aspects of the zonula occludens and presently available values for transepithelial electrical resistance was re-examined for the renal tubules. It was found that for the mammalian kidney a satisfactory correlation exists between the tight junction morphology and presently known functional parameters. This relationship is the more evident the more additional dimensional characteristics of the intercellular clefts are taken into consideration. It may therefore be concluded that, at least for the mammalian kidney, the assumption of differences in the molecular organization of the tight junctions is not needed to explain so far unresolved discrepancies between tubular morphology and function.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 213 (1980), S. 237-246 
    ISSN: 1432-0878
    Schlagwort(e): Stellate cell ; Nongranulated cell ; Adenohypophysis ; Rabbit ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Stellate cells in the rabbit adenohypophysis were observed electron microscopically under normal and experimental conditions such as lactation, thyroidectomy, adrenalectomy, or castration. In control animals stellate cells had a scanty cytoplasm surrounding the nucleus and possessed slender processes extending between granulated cells. The processes were interconnected by desmosomes to form a meshwork. In the cytoplasm, abundant microfilaments were present as well as ill-developed ordinary cell organelles, but secretory granules were absent. In the adenohypophysis of experimental groups, in which the granulated cells underwent characteristic changes, stellate cells also showed remarkable morphological alterations which were similar in all groups. In general, they became hypertrophied, and contained a well-developed Golgi apparatus and rough-surfaced endoplasmic reticulum. Lysosomes or lipid droplets were frequently encountered. Between adjacent stellate cells, intercellular canals were markedly developed and many microvilli were noticed. Based on the above data, it is suggested that the stellate cells are not only sustentacular elements, but play an important role in the function of the adenohypophysis, such as the supply of materials to granulated cells or the disposal of waste products.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 213 (1980), S. 311-324 
    ISSN: 1432-0878
    Schlagwort(e): Bombyx ; Silk-gland ; Starvation ; Development ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The cytological development of the silk gland has been studied by light and electron microscopy in silkworms experimentally starved at different periods of the natural feeding stage during the fifth instar. When newly molted animals are not provided with food, no sign of growth is observed. Starvation initiated early during the obligatory feeding period, stops cell growth and development of the organelles involved in protein synthesis and secretion, whereas it induces the appearance of organelles concerned with autolysis. These effects are reversible if starvation is not prolonged beyond two days. Starvation during the facultative feeding period, at the time of massive fibroin production, results in quantitative and qualitative modifications of organelles related to the decrease of fibroin production and the onset of autolysis. Rough endoplasmic reticulum, responsible for fibroin synthesis, forms transitory whorls. Fibroin transport via the Golgi apparatus and secretion of the protein into the gland lumen decrease parallel to fibroin synthesis, so that no fibroin storage can be detected in any organelle. After food deprivation, autophagosomes and secondary lysosomes rapidly develop in the cytoplasm, and if starvation continues portions of the cytoplasm are sequestered and completely destroyed. If animals are refed, fibroin production is resumed and autolysis declines. These ultrastructural alterations of the silk gland during experimental starvation are very similar to those observed during the periods of physiological starvation (molt and cocoon spinning) and generally considered to be under hormonal control. Our results raise the question of the nature of interactions between alimentary and hormonal factors which control silk-gland development.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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