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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 195 (1997), S. 503-514 
    ISSN: 1432-0568
    Keywords: Key words Nephrogenesis ; Basement membrane ; Interstitium ; Laminin ; PCNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Whilst antihypertensive, structural and functional roles have been proposed for the cells of the renomedullary interstitium in the adult kidney, little is known about its role in renal development. Rat kidneys were studied throughout development, prenatally at gestational ages E14–E21 and postnatally at 0–28 days, by light microscopy, transmission and scanning electron microscopy and following immunocytochemistry. Renomedullary interstitial cells were observed as early as embryonic day E14, forming a loose, orderly network around branches of the ureteric bud. Paralleling the development of the first nephron structures, renomedullary interstitial cells were arranged in a concentric circular manner around collecting ducts. Following tubular and vascular growth from the cortex into the medulla, this arrangement resulted in the characteristic ’rungs of a ladder’ appearance of interstitial cells between tubules, blood vessels and the collecting ducts. Renomedullary interstitial cells were closely adherent to basement membranes of tubules, blood vessels and collecting ducts from early in development. Contacts were absent between renomedullary interstitial cells and tubular structures in the process of remodelling, such as the hair-pin bends of the loops of Henle. At these foci laminin, a basement membrane glycoprotein was specificially localised to intracellular epithelial sites, whereas in more developed areas, laminin was restricted to epithelial basement membranes. Associated with the more mature structures, laminin was also localised to intracellular granules of renomedullary interstitial cells. Thus, renomedullary interstitial cells are present prior to and appear to be actively associated with tubule repositioning in the medulla, establishing themselves as integral to the process of renal development.
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  • 2
    ISSN: 1432-0878
    Keywords: Adrenal zona glomerulosa ; Ultrastructure ; Sodium depletion ; Sodium loading ; Sheep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of alterations in sodium status upon the morphology of the adrenal zona glomerulosa in sheep have been examined qualitatively and quantitatively, using lightand electron microscopy, and correlated with functionally related biochemical data. With severe sodium depletion induced by parotid-cannula drainage, there was mitotic activity throughout the zona glomerulosa, and glandular cells showed striking ultrastructural changes. These changes particularly affected mitochondria, which were enlarged, rounded and showed replacement of their normal lamelliform cristae by thin elongated cristal elements and bundles of tubular “rod-like” structures. Quantitative morphometric studies showed an increase in the volumes of zona glomerulosa cells, nuclei, mitochondria, smooth and granular endoplasmic reticulum, and Golgi profiles. In contrast, with dietary sodium loading, zona glomerulosa cells appeared shrunken and showed cytoplasmic lipid accumulation; mitochondria and other organelles were not significantly altered. The correlation of the ultrastructural cytological alterations in zona glomerulosa cells in sodium-depleted sheep with raised blood aldosterone levels suggests that such morphologic changes reflect a heightened capacity of these cells for aldosterone biosynthesis and secretion. These changes may also account for the increased sensitivity of the zona glomerulosa to aldosterone-producing stimuli during sodium deficiency.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 242 (1985), S. 505-510 
    ISSN: 1432-0878
    Keywords: Hyaluronic acid uptake ; Liver ; Liver endothelial cells ; Kupffer cells ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The uptake of [3H]acetyl-labelled hyaluronic acid (HA) Abbreviations used in this paper: HA hyaluronic acid; i.v. intravenous was examined in the liver, spleen and kidney of the rat after i.v. injection. 3H-activity was located by light- and electron-microscopic autoradiography after measurement by scintillation counting of tissue digests. In the liver, approximately 90% of the radioactivity was located in the sinusoidal endothelial cells, with autoradiographic grains distributed throughout the cytoplasm; 50% of the grains overlay vacuoles 0.3 to 1.2 μm in diameter. A few grains (4%) were located in Disse's space or nearby in the cytoplasm of hepatocytes. No grains were found in Kupffer cells. The remainder were randomly scattered across the sections in a pattern indicating nonspecific background activity. These observations are in accordance with the selective uptake of HA exhibited by dissociated liver cells in vitro. HA concentrations in the spleen and kidney were too low for detection by autoradiography. Splenic concentrations were much lower than in rabbits or mice; in this respect the uptake of circulating HA in the rat resembles that reported for chondroitin 4-sulphate.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 256 (1989), S. 419-429 
    ISSN: 1432-0878
    Keywords: Kidney ; Glomerulus ; Podocytes ; Tissue culture ; Electron microscopy ; Morphometry ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of rat glomerular epithelial cells (podocytes) in kidney slices in vitro was examined using qualitative and quantitative electron microscopy. The kidney slices were cultured in Medium 199 with Hanks' salts in a 5% CO2/95% O2 environment for up to 14 days. Few changes in podocyte ultrastructure occurred in the first 12 h of culture, but by 24 h cell bodies were rounded, microvilli were present on all podocyte surfaces, and some foot processes had been replaced by flattened expanses of cytoplasm. These changes were more pronounced by 3 days, when some podocytes had developed pseudopodal extensions and appeared to be migrating from glomeruli onto the slice surface. Podocytes could still be identified after 8, 10 and 14 days of culture, although relatively few glomeruli remained at 14 days. Morphometric methods were used to analyse podocyte shape, volume and surface area during the first 4 days of culture. The most significant change involved loss of foot processes: the number of filtration slits per 100 μm of basement membrane decreased from 211.8 ± 15.0 (mean ± SD) at the commencement of culture, to 55.3 ± 22.6 after 2 days (P 〈 0.001). These data provide baseline information for in vitro studies on the effects of nephrotoxins on podocytes.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 262 (1990), S. 203-203 
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0878
    Keywords: Prorenin ; Renin ; Granular juxtaglomerular cell ; Immunogold technique ; Exocytosis ; Mouse (BALB/c)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunogold techniques were used to investigate renin processing within granular juxtaglomerular cells following short-term (6 h and 1 day) and long-term (4 weeks) enalapril treatment in female BALB/c mice. In control animals, renin protein labelling was localized to all types of granules (proto-, polymorphous, intermediate and mature) and to transport vesicles, whilst prorenin labelling was found in all these sites except mature granules, confirming that active renin is localized to mature granules only. Following short-term enalapril treatment, the exocytosis of renin protein from mature granules was increased. Long-term enalapril treatment resulted in increased numbers of transport vesicles and all types of granules, consistent with increased synthesis and storage of renin. More large intermediate granules contained discrete regions labelled for prorenin. Renin protein was exocytosed from individual and multiple granules, whilst prorenin was exocytosed from protoand intermediate granules. It is concluded that under normal conditions prorenin is secreted constitutively by bulk flow from transport vesicles. On the other hand, active renin is secreted regulatively from mature granules. In conditions of intense stimulation (angiotensin-converting enzyme inhibition treatment), increased synthesis of prorenin leads to enhanced secretion of prorenin by both constitutive and regulative pathways. Under these conditions, the conversion of prorenin to active renin is increased, with increased secretion of active renin occurring in a regulative manner. Furthermore, the localization of prorenin to one discrete region of large intermediate granules leads us to conclude, that cleavage of the prosegment of renin occurs with the transition of intermediate to mature granules.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0878
    Keywords: Pregnancy ; Adrenal zona glomerulosa ; Juxtaglomerular apparatus ; Ultrastructure ; Sheep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural changes in the adrenal zona glomerulosa and renal juxtaglomerular apparatus have been examined during normal pregnancy in sheep. As pregnancy progressed, increasing numbers of cells in the adrenal zona glomerulosa displayed mitochondria with straight tubular “rod-like” structures replacing their normal lamelliform cristae; groups of cells showing these mitochondrial changes were predominantly located in the middle and superficial regions of the zona glomerulosa, but at all stages remained interspersed with cells with apparently normal mitochondria. In the same animals, the renal juxtaglomerular index was raised, reflecting an increase in renin storage, and juxtaglomerular myoepithelioid cells showed increased numbers of cytoplasmic granules, but no apparent increase in granular endoplasmic reticulum and Golgi profiles; there were no distinguishing morphological changes in juxtaglomerular peripolar cells. These findings provide morphologic evidence of stimulation of the adrenal zona glomerulosa in association with increased juxtaglomerular renin storage during pregnancy. The mitochondrial changes observed in an increasing proportion of cells in the zona glomerulosa closely resemble those seen in sodium-depleted animals, and may reflect the altered steroidogenic capacity of the adrenal gland in pregnant sheep. The finding of groups of cells displaying altered mitochondria lying next to cells with normal mitochondria suggests the presence of cells with different sensitivities to stimuli for aldosterone production or may indicate the presence of different cell types in the zona glomerulosa responding to different stimuli.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 260 (1990), S. 555-563 
    ISSN: 1432-0878
    Keywords: Glomerulus ; Podocytes ; Puromycin aminonucleoside ; Tissue culture ; Morphometry ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Puromycin aminonucleoside (PAN)-induced nephrosis in rats provides a model for studying the pathogenesis of severe proteinuric conditions, such as minimal change disease. The present study used scanning (SEM) and transmission (TEM) electron microscopy to investigate the in vitro effects of PAN on rat glomerular podocytes. Slices of rat kidney were incubated for up to 3 days in Medium 199 with Hanks' salts (control) or in medium with PAN. Semiquantitative SEM analysis of glomeruli on the upper surface of kidney slices indicated that incubation with PAN (100 μg/ml and 500 μg/ml) decreased the number of microvilli on podocyte cell bodies (days 1, 2 and 3), increased the number of glomeruli showing flattening of podocyte cell bodies and major processes (days 2 and 3), and increased the number of glomeruli showing surface membrane blebbing on podocyte foot processes (day 3) (p〈0.001 in all cases). TEM morphometry revealed that incubation with 500 μg/ml PAN retarded significantly (p〈0.001 at days 2 and 3) the loss of podocyte foot processes observed in control cultures. Whilst the SEM changes to podocyte ultrastructure largely mimic those seen in PAN nephrosis in vivo, the retardation of foot process loss runs counter to the major TEM change observed in vivo.
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  • 9
    ISSN: 1432-0878
    Keywords: Peripolar cells ; Juxtaglomerular apparatus ; Cytoplasmic granules ; Exocytosis ; Electron microscopy ; Sheep, newborn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Scanning and transmission electron microscopy were used to study the ultrastructural characteristics and positions of granulated peripolar cells in newborn lamb kidney. Following tissue fixation by vascular perfusion in situ, the vascular pole region of the glomerulus was exposed for examination by scanning electron micoscopy following removal of the glomerular tuft. Peripolar cells were recognized by their surface morphology enabling their quantification and an assessment of the relationship of their position in the renal cortex. The prominent expression of peripolar cells in this species was confirmed. Almost every vascular pole examined revealed peripolar cells (405 out of 407; 99.5%) and thus, throughout the cortex, the distribution of peripolar cells was the same as the distribution of renal corpuscles. Larger, more protruding peripolar cells were observed in the outer cortical renal corpuscles. The numbers of peripolar cells encircling each vascular pole ranged from 1 to 10. There was no correlation between number of granulated peripolar cells at the vascular pole and the position of the renal corpuscle within the renal cortex. As viewed by transmission electron microscopy, organelles of protein synthesis were abundant in the cytoplasm of peripolar cells. Exocytosis of cytoplasmic granules was observed by both scanning and transmission electron microscopy implying that a process of regulative secretion occurs from these cells. The use of ultrastrural techniques has provided evidence supporting the concept that peripolar cells are prominent in the cuff region of each renal corpuscle of the newborn lamb and further-more that peripolar cells in this species most likely have a secretory function.
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  • 10
    ISSN: 1432-0878
    Keywords: Kidney ; Glomerulus ; Stereology ; Morphometry ; Disector ; Quantitative methods, structural ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Alterations in numbers of glomeruli and glomerular cells occur in various renal disorders. Although values for these parameters have previously been reported for several species, the estimates have often been biased due to assumptions regarding glomerular and/or nuclear size and shape. Other studies have used tedious serial-section reconstruction methods. In the present study, unbiased stereological methods were used to estimate total numbers of glomeruli and individual glomerular cell types in normal rats. The kidneys of seven adult Sprague-Dawley rats were perfused with 4% paraformaldehyde and 1% glutaraldehyde in phosphate buffer and embedded in either glycolmethacrylate (for light microscopy, LM) or Epon/Araldite (for transmission electron microscopy, TEM). Total glomerular number was estimated using an LM physical disector/fractionator combination; the total number of cells per average glomerulus was estimated using an LM optical disector/ Cavalieri combination; and TEM physical disectors were used to count individual cell types. The normal rat kidney was found to contain 31764±3667 (mean±SD) glomeruli. An average glomerulus contained 674±129 cells, of which 181±53 were epithelial cells (podocytes), 248±53 were endothelial cells, and 245±45 were mesangial cells. An average renal corpuscle contained 117±27 parietal epithelial cells. Following sectioning and staining, less than 6.5 h was needed to obtain the above estimates for a single animal, with coefficients of variation (SD as a percent of the mean) ranging from 10% to 25%. The unbiased stereological methods used in the present study constitute an unbiased, precise and cost-efficient set of quantitative tools for assessing glomerular morphology in health and disease.
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