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  • 1
    ISSN: 1432-0878
    Keywords: Development ; Liver ; Peroxisomes ; Catalase ; Biogenesis ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Hepatic peroxisomes in human embryos with a menstrual age of 6 and 7 weeks have been examined via catalase cytochemistry. In the younger sample, the organelles show no catalase activity, their matrix being pale and coarsely reticular. In the 7-week specimen, the peroxisome population consists of catalase-positive and catalase-negative organelles. The latter have a morphology identical to that of the 6-week sample and represent 66% of the population. The positive organelles show a pronounced staining hetereogeneity. Together with the simultaneous presence of negative organelles, this might reflect the onset of catalase import into the peroxisomes during this period. Catalase heterogeneity excludes a continuous exchange of matrix contents; moreover, interconnections between peroxisomes have not been observed, and no cluster formation occurs. The data therefore also suggest that catalase is imported into individual, preexisting organelles in embryonic liver. The three peroxisomal β-oxidation enzymes become detectable by immunocytochemistry only later during development. Morphological indications for a rapidly dividing population, such as elongated and/or tailed organelles, have not been observed. Morphometry has revealed that, in these early stages, the organelles are significantly smaller than the peroxisomes of fetal and adult human liver.
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  • 2
    ISSN: 1432-0878
    Keywords: Neural lobe, pituitary ; Anterior lobe, pituitary ; Intermediate lobe cleft, pituitary ; Morphometry ; Vascular corrosion casts ; Venules ; Capillaries ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We applied scanning electron microscopy combined with imaging and morphometric techniques to analyze the dorsal topography and morphology of short portal vessels linking the capillary beds of the pituitary neural and anterior lobes in adult male albino rats. The pituitary microvasculature was replicated by intracarotid injection of Batson's No. 17 compound producing plastic casts that were advantageous for comprehensive morphometric analyses using an imaging device. The analysis revealed the existence of two types of portal vessels having quantitatively different morphological properties. The bilateral venular plexus of 3–4 vessels located at the base of the infundibular stalk (each venule measuring 300 μm in length and 32 μm in diameter) appears to be the major part of the short portal system in the dorsum of the rat pituitary gland. Narrower capillary-like shunt vessels (6.8 μm in diameter), of about the same length as the venules, were situated throughout other subregions of the intermediate lobe cleft. The short portal vessels of both types made direct anastomoses with the capillary networks in the neural and anterior lobes. The neural lobe capillaries were twice as numerous (1324 per mm2), and only half as wide (6.2 μm), as the sinusoidal capillaries in the anterior lobe (density of 637 per mm2; diameter of 13.7 μm). The topographical position of the portal venular system suggests that the caudolateral subregions of the pituitary neural and anterior lobes have a functional relationship dependent on rapid interlobe transfer of neurohumoral factors such as hormones via the portal blood. This process appears to be supplemented throughout the rest of the cleft between the two lobes by a small number of capillary shunts that supply the epithelial cell lobules of the intermediate lobe in situ. The findings collectively indicate that this portal system provides a constant stream of neurohumoral information that is shared moment-by-moment between the pituitary neural and anterior lobes.
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  • 3
    ISSN: 1432-0878
    Keywords: Colon ; Immunocytochemistry ; Intestine large ; Ionic regulation ; Na+ ; Domestic fowl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have used polyclonal antibodies generated against purified bovine renal amiloride-sensitive Na+ channels to localize amiloride-sensitive Na+ channels within the lower intestine (colon and coprodeum) of the hen. These antibodies cross-reacted with two polypeptides exhibiting Mr's of 235 and 150 kDa on immunoblots of detergent-solubilized apical membrane fractions from both the colon and coprodeum. The apparent molecular masses of theses polypeptides are in agreement with the Mr's of 2 of the subunits of the renal high amiloride-affintiy Na+ channel, namely the α and the β(=amiloride binding) subunits. The cellular distribution of Na+ channels was determined by immunoperoxidase and indirect immunofluorescence cytochemical techniques. The apical (luminal) membrane and cytoplasm of villar principal cells in both colon and coprodeum exhibited immunoreactivity, whereas goblet cells were nagative. Both principal and goblet cells of the crypts were also negative. We conclude that the amiloride-sensitive Na+ channels are localized to the principal cells of the intestinal villi and that these cells are responsible for intestinal Na+ absorption.
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  • 4
    ISSN: 1432-0878
    Keywords: Histamine ; Immunohistochemistry ; Brain, vertebrate ; Catecholamines ; Triturus carnifex (Urodela)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution of immunoreactivity for histamine was studied in the brain of the urodele Triturus carnifex using the indirect immunofluorescence method. Histamine-immunoreactive cell bodies were localized in the caudal hypothalamus within the dorsolateral walls of the infundibular recesses. These immunoreactive cell bodies were pear-shaped, bipolar and frequently of the cerebrospinal-fluid-contacting type. Histaminergic nerve fibers were detected in almost all parts of the brain. Dense innervation was seen in the telencephalic medial pallium and ventral striatum, the neuropil of the preoptic area, the septum, the paraventricular organ, the posterior commissure, the caudal hypothalamus, the ventral and lateral mesencephalic tegmentum. Medium density innervation was observed in the lateral mesencephalic tegmentum and optic tectum. Poor innervation was present in the telencephalic dorsal pallium and in the central gray of the medulla oblongata. Few fibers occurred in the olfactory bulbs and in the telencephalic lateral pallium. Double immunofluorescence staining, using an antibody against tyrosine hydroxylase, showed that histamine-immunostained somata and those containing tyrosine-hydroxylase-like immunoreactivity were co-distributed in the tuberal hypothalamus. No co-occurrence of histamine-like and tyrosine hydroxylase-like immunostaining was seen in the same neuron. The pattern of histamine-immunoreactive neurons in the newt was similar to that described in other vertebrates. Our observations, carried out on the apparently simplified brain of the newt confirm that the basic histaminergic system is well conserved throughout vertebrates.
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  • 5
    ISSN: 1432-0878
    Keywords: Keratinocyte subpopulations ; Epidermal calcium-binding protein ; Low gravity sedimentation ; Immunoblotting ; Immunocytochemistry ; Flow cytometry ; Rats (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Epidermal calcium-binding protein (ECaBP) is present in the cells of the basal layer of the epidermis and other stratified epithelia. Since the basal layer compartment contains at least two types of cells: slow-cycling, poorly-differentiated, and actively proliferating, more differentiated cells, it was of interest to determine whether they both contained ECaBP. Basal and nearly suprabasal layer keratinocytes from newborn rat epidermis were fractionated into three fractions on the basis of cell size, using low-gravity sedimentation. The cell differentiation in each subgroup was estimated by cell size, morphology, cell cycle stage, RNA/DNA content, and the presence of specific keratins. The presence of ECaBP in these fractions was detected by immunocytochemistry and immunoblotting. Double staining with ECaBP antibodies and propidium iodide followed by flow cytometry was used to correlate ECaBP production and the stage of cell cycle. The relative cell size, measured by the light scattering was used to study the relationship between cell size and ECaBP production. The results show that small keratinocytes with low DNA and RNA content (G0 cells) do not express ECaBP. ECaBP was found only in intermediate size basal keratinocytes with higher DNA and RNA contents, corresponding to actively proliferating S phase cells. Large keratinocytes, which express suprabasal keratin and have low DNA and high RNA content, cease to express ECaBP. ECaBP may, therefore, be a useful marker for assessing the movement of cells from poorly differentiated reserve compartment towards proliferation and further differentiation in both physiological and pathological situations.
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  • 6
    ISSN: 1432-0878
    Keywords: Retina ; Müller cells ; Neuron-specific enolase ; Immunocytochemistry ; Quantitative analysis ; Ultrastructure ; Bufo marinus (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have previously shown that an antibody against neuron-specific enolase (NSE) selectively labels Müller cells (MCs) in the anuran retina (Wilhelm et al. 1992). In the present study the light- and electron-microscopic morphology of MCs and their distribution were described in the retina of the toad, Bufo marinus, using the above antibody. The somata of MCs were located in the proximal part of the inner nuclear layer and were interconnected with each other by their processes. The MCs were uniformly distributed across the retina with an average density of 1500 cells/mm2. Processes of MCs encircled the somata of photoreceptor cells isolating them from each other by glial sheath, except for those of the double cones. Some of the photoreceptor pedicles remained free of glial sheath. Electron-microscopic observations confirmed that MC processes provide an extensive scaffolding across the neural retina. At the outer border of the ganglion cell layer these processes formed a non-continuous sheath. The MC processes traversed through the ganglion cell layer and spread beneath it between the neuronal somata and the underlying optic axons. These processes formed a continuous inner limiting membrane separating the optic fibre layer from the vitreous tissue. Neither astrocytic nor oligodendrocytic elements were found in the optic fibre layer. The significance of the uniform MC distribution and the functional implications of the observed pattern of MC scaffolding are discussed.
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  • 7
    ISSN: 1432-0878
    Keywords: Skeletal muscle ; Macrophages ; Phagocytosis ; Degeneration ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Two soleus muscles with degenerating muscle fibres were serially sectioned and adjacent sections from various levels of the skeletal muscles were stained with antibodies that react with either monocytes and inflammatory macrophages (ED1) or with the major subpopulations of resident macrophages (ED2 and ED3). ED2+ and ED3+ resident macrophages were abundant throughout the muscles but were not present within the degenerating fibres. ED1+ cells, in contrast, were rarely observed within the undamaged regions of the muscles but were abundant within the degenerating fibres and in the perimysium between arterioles and degenerating fibres. It is concluded that the phagocytosis of damaged muscle fibres is not carried out by the major subpopulations of resident macrophages.
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  • 8
    ISSN: 1432-0878
    Keywords: Spinal cord ; Motoneurones ; Dorsal horn ; Neurofilament ; Phosphorylation ; Immunocytochemistry ; Rat ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Neurofilament immunoreactivity was examined in spinal cords of rats and cats with antibodies to all three subunits (68 kD, 155 kD and 200 kD) and to different phosphorylation states of 200 kD. NFHP-, an antibody against non-phosphorylated 200 kD, labelled all rat neuronal perikarya but failed to labet cat neurofilaments. In both species, the perikarya and processes of motoneurones were immunoreactive for all three subunits but most dorsal horn neuronal perikarya were not immunoreactive for 68 kD and 155 kD. Motoneuronal perikarya and proximal processes showed filamentous labelling for 68 kD but not for 155 kD in the rat, while in neither species did these show labelling with RT97, an antibody against a highly phosphorylated form of 200 kD; immunoreactivity for 200 kD was present in both filamentous (probably partially phosphorylated) and non-filamentous (non-phosphorylated) forms, but in dorsal horn neurones only the latter was present. Interpretations consistent with this data are: in rat and possibly also cat, motoneuronal neurofilaments consist of a 68 kD backbone with partially phosphorylated 200 kD sidearms, with both 155 kD and 200 kD (non-phosphorylated) subunits in a non-filamentous form; this neurofilament becomes more highly phosphorylated along the proximal processes. The dorsal horn neurones probably contain 200 kD in a non-filamentous form but may lack the other subunits.
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  • 9
    ISSN: 1432-0878
    Keywords: Caudal neurosecretory system ; Urophysis ; Urotensins ; Immunohistochemistry ; Development, ontogenetic ; Oncorhynchus keta (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In order to make an immunohistochemical analysis of the development of the caudal neurosecretory system of the chum salmon, Oncorhynchus keta, we employed the peroxidase-anti-peroxidase technique using antisera specific for urotensins (U) I and II on artificially reared embryos, larvae, and juveniles of this species. Immunoreactivities for UI and UII were first demonstrated in the embryo immediately before hatching, showing labeled perikarya and fibers in the most caudal region of the spinal cord where the presumptive caudal neurosecretory system is located. However, distinct differentiation of the histological neurohemal organ had not yet begun in the embryo. Immunoreactive perikarya and fibers gradually increased in number, and an elaborate urophysis comparable to that of adults was demonstrated in the larvae about 5 months after hatching. At this stage, weak immunoreactivity against UI was detected in the neurohypophysis.
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  • 10
    ISSN: 1432-0878
    Keywords: Globule leukocytes ; Mucosal mast cells ; Granular intraepithelial lymphocytes ; natural killer cells ; Development ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The changes in the number, distribution, and ultrastructure of globule leukocytes (GL) during postnatal development were investigated in the intestinal epithelium of non-infected healthy rats. Intestinal GL were abundant in normal newborn rats even in the absence of infection. They subsequently decreased markedly to the adult level by the fourth week. Ultrastructurally, morphological variations suggesting maturation of the cells were observed in the GL during development. These changes could be noted neither in the mucosal mast cells (MMC) nor in the granular intra-epithelial lymphocytes. Morphological differences between GL and other cells were evident in adult animals. Most notably, paracrystalline structures were found exclusively in the granules of the GL. Immunohistochemically, both the GL and MMC were stained with anti-serotonin, but not with anti-IgE. Degranulation of GL in developing rats was caused by repeated intraperitoneal administration of dexamethasone. Neither GL nor MMC were affected by compound 48/80. These results indicate that (1) the GL and MMC are derived from a common ancestral cell toward the end of embryonic development, (2) the immature GL migrate from the lamina propria into the epithelium to differentiate, mature, and proliferate, and (3) the immature GL have specific functions during the neonatal period.
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