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  • Rat (Wistar)  (7)
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  • 1
    ISSN: 1432-0878
    Keywords: Calbindin ; Neurohypophysis ; Development, ontogenetic ; Immunohistochemistry ; In-situ hybridization ; Electron microscopy ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Spot 35 protein is a Ca-binding protein originating from the rat cerebellum; it is now referred to spot 35-calbindin. This protein is expressed in immature pituicytes of the neurohypophyseal anlage in the E11–E18 rat embryo. The gene expression of spot 35-calbindin was detected by in-situ hybridization analysis only at stage E11–E12. Profiles of spot 35-positive nerve fibers of a neurosecretory nature were found in anlage at stage E16. At this stage, some immature pituicytes are partially immunopositive for spot 35-calbindin only in their peripheral cytoplasm; others are immunonegative. At birth and thereafter through adulthood, abundant nerve fibers are the sole structures immunoreactive for spot 35-calbindin; all the pituicytes are immunonegative, resulting in a light-microscopic appearance of numerous immunonegative round profiles, corresponding to pituicytes, and capillaries embedded in the granularly immunostained neurohypophysis. The present findings suggest that, during specific embryonic stages, immature pituicytes exert some as yet unidentified roles related to Ca-mediated functions involving the expression of spot 35-calbindin.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 270 (1992), S. 165-172 
    ISSN: 1432-0878
    Keywords: Thoracic aorta ; Smooth muscle cell ; Cytoarchitecture ; Morphometry ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cytoarchitecture of the medial layer of rat thoracic aorta was examined by scanning electron microscopy after removal of the connective tissue. The outermost lamella showed a lattice-like structure of muscle bundles of closely apposed smooth muscle cells (SMCs), whereas the inner lamellae consisted of more-or-less continuous muscle sheets of vaguely defined subgroups of parallel SMCs. Longitudinal rows of ridges ran along the adventitial surface of these muscle bundles and sheets. The SMCs of the outermost lamella, were 5.1 μm wide, and varied in shape, whereas those of the inner lamellae, were 52.7 μm long, 2.6 μm wide and 4.1 μm thick, and were elongated, spindle-shaped cells with serrated outlines. These latter SMCs extended obliquely, and partially overlapped each other. The surface of the SMCs in the outermost lamella exhibited a rugged texture, with nodular protrusions and oblique and longitudinal laminar folds, while the inner lamellar cells showed longitudinal laminar folds and finger-like processes on both sides of the ridges, pointing in opposite directions to the ridges. The angle of deviation from the transverse axis of the vessel, of the muscle bundles and subgroups in the outermost lamella, was 33.6°, in the second and third lamellae, 22.5°, and in the innermost lamellae, 12.8°. The mean angle of the muscle bundle and subgroup arrangement, with respect to the long axis of the vessel, however, was basically 90° in all lamellae.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0878
    Keywords: Juxtaglomerular cells ; Circadian rhythm ; Plasma renin activity ; Plasma angiotensinogen concentration ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Subcellular structures of juxtaglomerular (JG) cells in the rat kidney were morphometrically examined at six evenly spaced times over 24 h. Plasma renin activities and angiotensinogen concentrations were also measured at these times. The cell volumes were larger at 20.00 h and 04.00 h than at 00.00 h, whereas the nuclear volumes peaked at 20.00 h and 08.00 h, decreasing at 00.00 h and 16.00 h. The volume and surface densities of renin granules and their individual volumes and surface areas peaked at 16.00 h and 00.00 h, decreasing at 20.00 h and 08.00 h, whereas their numerical densities peaked at 20.00 h, decreasing at 12.00 h. The surface densities of the rough endoplasmic reticulum (rER) peaked at 20.00 h, decreasing at other times, except at 08.00 h, when rER volume and surface density were relatively high. The plasma renin activity was maximal at 20.00 h, whereas it was minimal at 08.00 h. The variation in plasma angiotensinogen concentrations was inversely correlated with that in plasma renin activities. These results suggest that JG cells actively synthesize and release renin during the dark period, especially at 20.00 h, whereas during the light period they gradually synthesize renin and produce the granules, most of which may be stored in the cells during this period.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 256 (1989), S. 347-353 
    ISSN: 1432-0878
    Keywords: Lung ; Type II cell ; Subcellular structures ; Morphometry ; Crcadian rhythm ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Subcellular structures of type II alveolar epithelial cells in the rat lung were analyzed at six evenly spaced times over 24 h (light period: 06.00 h–18.00 h), using a morphometric technique. The cell volumes were maximal at 16.00 h and minimal at 08.00 h. The volume and surface densities of rough endoplasmic reticulum and mitochondria were low during the light period, and high during the dark period. Morphometric parameters of multivesicular bodies did not significantly fluctuate over 24 h, but they increased from 04.00 h to 08.00 h. The volume densities of lamellar bodies increased from 16.00 h to 20.00 h, and decreased from 00.00 h to 08.00 h. The change in numerical densities of lamellar bodies was inversely correlated to that in the volume densities. As shown by electron microscopy, small lamellar bodies predominated at 08.00 h, larger lamellar bodies increasing at 16.00h. Composite bodies often appeared at 08.00 h and 12.00 h. Type II cells thus appear to fluctuate, showing three phases over 24 h: formation, accumulation and secretion of lamellar bodies. In particular, it is noteworthy that the accumulation stage occurs during the resting phase of the rat, whereas the secretion stage occurs during its body-active phase.
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  • 5
    ISSN: 1432-0878
    Keywords: Thyroid gland ; Cathepsin B ; Lysosomes ; Immunocytochemistry ; Diurnal rhythm ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunocytochemical localization of cathepsin B and thyroxine (T4) in follicular cells of the rat thyroid gland and plasma concentrations of thyroid stimulating hormone (TSH) were examined at six evenly spaced times over 24 h. By light- and electron microscopy, immunodeposits for cathepsin B were localized in cytoplasmic granules of various sizes, whereas those for T4 were detected mainly in larger granules of the cells and in the colloid lumen. The size and location of cytoplasmic granules showing immunoreactivity for cathepsin B and T4 in the cells varied over 24 h, corresponding to a change in plasma TSH concentrations. These immunopositive large granules appeared in the apical cytoplasm at 12.00 h, when the level of TSH was highest. At 20.00 h when the level of TSH was lowest, T4-positive granules almost disappeared, and cathepsin B-positive small granules were abundantly seen in the basal region. From 00.00 h to 08.00 h, these positive granules changed in the same manner as those seen from 12.00 h to 20.00 h, associated with an increase in plasma TSH levels. These results suggest that newly formed colloid droplets migrate from the apical to the basal regions. Cathepsin B may play a role not only in the degradation of thyroglobulin but in the maturation of thyroid hormones during the migration of the granules.
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  • 6
    ISSN: 1432-0878
    Keywords: Pancreas, endocrine ; Morphometry ; Plasma glucose ; Plasma insulin ; Circadian variation ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Variations in stomach weights, plasma glucose and insulin levels in the portal vein, and in subcellular structures of rat pancreatic islet B-, A- and D-cells were examined over 24 h. The variation in stomach weights paralleled plasma glucose levels, indicating that the levels may be influenced by intestinal glucose absorption. Plasma insulin levels increased from the late dark to the early light periods, whereas they decreased from the late light to the early dark periods. The variation in plasma insulin levels was in the opposite sense to that in the relative numbers of B-cell granules. The decrease in the relative numbers of A-cell granules occurred between the late dark and early light periods. The relative numbers of D-cell granules decreased before and after the decreases in B- and A-cell granules. The variation in D-cell granules appears to correspond to the inhibitory effect of somatostatin. The relative amounts of rough endoplasmic reticulum (rER) in each cell varied in a reciprocal manner to those of B-cell granules. Moreover, the variation in plasma insulin levels coincided with variations in rER of hepatocytes and pancreatic acinar cells. The changes in rER of each cell may correlate with the trophic effect of insulin.
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  • 7
    ISSN: 1432-0878
    Keywords: Atrial myoendocrine cells ; Morphometry ; Plasma atrial natriuretic peptides ; Circadian variations ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Subcellular structures of atrial myoendocrine cells in the rat heart and plasma concentrations of atrial natriuretic peptides (ANP) were examined at six evenlyspaced time points over 24 h, using morphometric techniques and radioimmunoassay. Myofibrils and mitochondria of the cells occupied 73.3% of the cytoplasm; 2% of the cytoplasm was occupied by secretory granules, rough endoplasmic reticulum and Golgi complexes, structures characteristic of endocrine cells. Plasma ANP concentration was maximal at 08.00 h, when the individual volume of secretory granules was minimal. The numerical density of secretory granules was increased at 12.00 h. The plasma ANP concentration was minimal at 20.00 h, when the numerical density was minimal and the individual volume was maximal. The fluctuation in plasma ANP concentrations over 24 h was thus parallel to that in the numerical densities of secretory granules and inverse to that in individual volumes. These results suggest that in rats the secretory activity of atrial myoendocrine cells increases at the beginning of the resting period, whereas it decreases at the beginning of the active phase.
    Type of Medium: Electronic Resource
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