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  • Rat  (24)
  • Springer  (24)
  • 2000-2004  (1)
  • 1980-1984  (14)
  • 1975-1979  (9)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 34 (1982), S. 376-381 
    ISSN: 1432-0827
    Keywords: Matrix vesicles ; Bone ; Actin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Preliminary indications of the occurrence of actin and myosin in crude matrix vesicle preparations have been reported previously. In the present study extracellular matrix vesicles from rat alveolar bone were isolated. They were further purified by a sucrose density gradient. SDS-polyacrylamide gel electrophoresis of the purified vesicles revealed the presence of a polypeptide with a molecular weight of 43 K daltons and with electrophoretic mobility identical to that of blood platelet actin. The limited proteolysis of both 43 K dalton vesicular polypeptide and actin byStaphylococcus aureus-V8-protease revealed three fragments with identical electrophoretic mobility. In addition, the vesicular preparations inhibited the activity of DNase I, a property typical of actin monomers. Filamentous material extracted from matrix vesicles showed ultrastructural features of F-actin. Reaction of this material with heavy meromyosin resulted in arrowhead formation, which is characteristic of acto-heavy meromyosin. The occurrence of actin in extracellular matrix vesicles may account for their budding from the osteoblastic plasma membrane, their possible motility in the matrix, and maintenance of the spherical shape.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 28 (2000), S. 128-134 
    ISSN: 1573-9686
    Keywords: Hippocampus ; Vigilance states ; Paired-pulse ; Dentate gyrus ; Dentate granule cells ; Evoked response ; Rat ; In vivo studies ; Perforant path ; Maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract This study examined the effect of normal development and vigilance state on the modulation of dentate granule cell activity in the freely moving rat at 15, 30, and 90 days of age across three vigilance states: quiet waking, slow-wave sleep, and rapid eye movement sleep. Using paired-pulse stimulation, the paired-pulse index (PPI) was obtained for the dentate evoked field potentials elicited by the stimulation of the medial perforant path. Although significant differences in PPI values were observed during development, no significant vigilance state related changes were obtained. Preweaning infant rats, i.e., 15-day old, exhibited significantly less early (interpulse intervals, IPI= 20–50 ms) and late (IPI = 300–1000 ms) inhibition, and less facilitation (IPI = 50–150 ms) when compared to the 90-day old adult rats during all three vigilance states. PPI values obtained from the 30-day old group fell intermediate between the 15- and 90-day old animals. These changes in PPI values provide a quantitative measure of changes in the modulation of dentate granule cell excitability during normal maturation. They can now can be used to evaluate the impact of various insults, such as prenatal protein malnutrition or neonatal stress, on hippocampal development. © 2000 Biomedical Engineering Society. PAC00: 8717Nn, 8719La, 8719Nn
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 172 (1976), S. 133-144 
    ISSN: 1432-0878
    Keywords: Cornea ; Nerves ; Rat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the corneal nerves of the rat was studied in tissue fixed by immersion in and by perfusion with glutaraldehyde-containing fixatives. Of the four types of axonal terminal identified in the nerves, those with the features of adrenergic and cholinergic terminals were confined to the nerves at the limbus and were concentrated in the perivascular plexuses. The remaining two types of terminal were found on axons located in all parts of the cornea and on both intraepithelial axons and axons in the stromal nerves. Of these, one contained the numerous mitochondria which occur in the terminals of axons associated with known mechanoreceptors and the second contained variable and often small numbers of both clear and large dense-cored vesicles. While most of the mitochondria-containing terminals were seen in nerves located near the periphery, vesicle-containing terminals were numerous in all of the nerves, and especially in those in the avascular cornea. In material fixed by immersion in glutaraldehyde-paraformaldehyde, the vesicle-containing terminals appeared to be dilated, but in material fixed by perfusion there was little evidence of any increase in the diameter of the axons in the terminal regions. The structure of the terminals was compared with that of the terminals of axons identified in the nerves of the skin and the urinary tract and the differences in the vesicle content of the terminals to those reported in other studies of the corneal nerves was related to the use of different fixation procedures. The possibility that axons possessing such terminals are identical with the beaded axons and both the cholinesterase-positive and fluorescent axons demonstrated in light microscopical studies of the corneal nerves is discussed, and the widespread distribution of the axons in the cornea is equated with the hypothesis that they are afferent in nature and represent the peripheral receptors for pain impulses.
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  • 4
    ISSN: 1432-0878
    Keywords: Ovarian autografts ; Autonomic innervation ; Ovarian steroids ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ovaries were removed from female rats and immediately autografted into a subcutaneous pouch in the flank in order to quantitate the relationship of graft re-innervation, steroid secretion and vaginal smear pattern. Animals were killed at three time periods: three days after grafting, on the first day a cornified vaginal smear appeared and at the first metestrus. In addition, control animals were killed at metestrus. Plasma samples were obtained from all rats and analyzed for estradiol-17β and progesterone concentration by radioimmunoassay. At the first day of vaginal cornification after grafting, plasma estradiol-17β (45.8±4.0 pg/ml) was elevated in comparison to controls at metestrus (24.0±2.6 pg/ml), but plasma progesterone (21.5±4.0 ng/ml) was not different (30.6±1.7 ng/ml). Subsequently, at the first metestrus following grafting, plasma estradiol-17β (23.0±3.5 pg/ml) was comparable to control values. In contrast, progesterone was decreased (17.5±1.9 ng/ml). A definite correlation was detected between the vaginal smear and plasma levels of steroid hormones in the castrated female rat with subcutaneous ovarian autografts. Histochemical techniques were used to study the adrenergic and cholinergic innervations of grafts three days after grafting, at the first day of vaginal cornification, and at the first metestrus. No correlation was shown between density of adrenergic or cholinergic innervation and plasma levels of estradiol-17β and progesterone or onset of a cycling vaginal smear.
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  • 5
    ISSN: 1432-0878
    Keywords: Splenic implants ; Non-lymphoid cells ; Trapping ; Enzyme histochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Regeneration of splenic tissue after autologous subcutaneous implantation provides a useful model for studying the development of splenic tissue. The development of the various non-lymphoid cells of the white pulp in the rat is described. It appears that regeneration of the implants is initiated by ingrowing vessels and a newly formed reticulum, which forms the microenvironment for the homing lymphocytes. Marginal metallophils are found at their characteristic location at the inner border of the marginal sinus five weeks after implantation. Trapping of antigen-antibody complexes reappears when the first primary follicles can be recognized.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 217 (1981), S. 397-403 
    ISSN: 1432-0878
    Keywords: Pituitary gland ; Rat ; MSH-cells ; Pimozide ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of pimozide, a dopamine receptor-blocking agent, were studied in the pars intermedia of the rat. The animals received 100 μg/100 g pimozide daily for 2, 5, 10, 15, and 20 days. Pimozide induces ultrastructural changes after 5 days of treatment. About 50% of the MSH-cells display characteristics of stimulation. Their cytoplasm is partially or totally depleted of secretory granules. The rough endoplasmic reticulum displays a network of interconnecting cisternae and ribbon-like structures. The well-developed Golgi complexes exhibit numerous dilatations of their cisternae, which contain electron-dense material. The nerve endings are not altered. Twenty days after treatment, the above-described changes have not decreased in magnitude. The present findings suggest that pimozide stimulates the mechanism of synthesis and release in some MSH-cells, most probably the elements underlying an inhibitory dopaminergic control.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 168 (1976), S. 261-270 
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Exercise ; Rat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Four groups of male rats were exercised for periods of 2, 4, 6, and 8 weeks with controls in each group. As a result of chronic exercise there was an increase in the width of the zona fasciculata of the adrenal cortex. Also, there was an increase in the number and size of the mitochondria, and an increase in the quantity of smooth endoplasmic reticulum, and during the first 4 weeks of exercise an increase in the number of lipid droplets in the zona fasciculata. The close relationship between the smooth endoplasmic reticulum and the mitochondria, and the relationship between the smooth endoplasmic reticulum and the lipid droplets suggests a possible means for a transport mechanism for movement of precursors between these organelles.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 173 (1976), S. 529-542 
    ISSN: 1432-0878
    Keywords: Capillaries ; Cerebral cortex ; Endothelial cells ; Intraendothelial lumen ; Interendothelial lumen ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Developing blood vessels in rat cerebral cortex were studied at a number of stages between 3 and 28 days postnatal, in an attempt to obtain data on the mechanisms by which the lumen is established within cords of mesodermal cells. A combination of techniques was utilized in an attempt to elucidate these mechanisms. These were: (a) aldehyde fixation and block staining with phosphotungstic acid; (b) aldehyde perfusion followed by perfusion of a lead solution and post-fixation in osmium tetroxide; (c) conventional preparation of tissue with aldehyde and osmium fixation. Support for interendothelial lumen formation was readily forthcoming, including vessels with junctions between two or more endothelial cells cut transversely. There was some support for intraendothelial lumen formation, in the form of “seamless” endothelial cells. Other features noted included the presence of free ribosomes and vacuoles in the endothelial cells, endothelial flaps, sprouts and tendrils, intraluminal debris, endothelial degeneration and a junction with a nonendothelial cell. Large numbers of endothelial vacuoles were noted, many of them occurring at the abluminal edge of the cells. These vacuoles may be involved in the formation of intraendothelial lumina and also in the enlargement of both types of lumina. This study provides evidence that besides the well-established inter-endothelial lumen formation, intraendothelial mechanisms may also be operative in rat cerebral cortex. The techniques employed in this study offer the potential for clarifying these and related issues.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 171 (1976), S. 375-379 
    ISSN: 1432-0878
    Keywords: Corpus luteum ; Autografts ; Rat ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The rat ovary has been transplanted successfully to subcutaneous tissue areas by several investigators. Light microscopy has revealed that corpora lutea in ovarian autografts are formed by luteinization of intact follicles and contain entrapped ova. In the present study, corpora lutea from autografted ovaries in castrate rats were obtained at metestrus and examined electron microscopically to determine whether their cellular morphology correlated with the normal progesterone levels in these animals. Cellular features usually accepted as regressive were apparent. The findings suggest either structural luteolysis is occurring before functional luteolysis or that the adrenal has increased steroidogenic activity in the castrate with ovarian autografts to account for the normal progesterone levels.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 196 (1979), S. 237-247 
    ISSN: 1432-0878
    Keywords: Liver ; Kupffer cells ; G6PDH activity ; Histochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The aim of this study was to identify the G6PDH-active sinusoidal cells in the rat liver described by Rieder et al. (1978). Because of their number and distribution in the liver parenchyma, endothelial cells and pit cells could be excluded. Fat-storing cells were specifically marked by vital staining with vitamin A and identified by fluorescence microscopy. Kupffer cells could be detected after vital staining with carmine. Both staining methods allowed a subsequent incubation for the demonstration of G6PDH activity in the same unfixed cryostat section. Whereas more than 80% of the fluorescent particles were found outside the enzyme-positive cells, all G6PDH-active cells contained carmine particles. After counting the G6PDH-active cells, an estimation of 0.217 × 108 cells/g liver tissue was obtained. The results indicate that high G6PDH activity is common to all Kupffer cells, and is therefore a highly specific marker enzyme for this class of sinusoidal liver cells.
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