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  • Peripolar cells  (4)
  • Exocytosis  (3)
  • Immunohistochemistry  (2)
  • 1
    ISSN: 1432-0878
    Keywords: Atrial appendage ; Atrial-specific granules ; Atrial natriuretic polypeptides ; Exocytosis ; Ultrastructure ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Atrial appendage cardiocytes of mammals, including man, contain multiple cytoplasmic granules that vary in number in different physiological states. Using morphologic and comprehensive morphometric techniques, these granules were assessed in Sprague-Dawley rats following dehydration for 5 days, volume-loading by substituting 1% NaCl as drinking water for 7 days, unilateral nephrectomy plus volume-loading for 7 days, and in late term pregnant animals (18–20 days; term ≈21 days). Although principally located in the paranuclear region, granules were observed throughout the sarcoplasm. Cytological features indicative of synthetic activity and granule formation were readily apparent in all groups with the exception of pregnant rats where they were infrequently observed. Granule contents were released by exocytosis and observed in the right appendage of control, dehydrated and nephrectomy/volume-loaded groups and left appendage of volumeloaded animals. Exocytosis was not observed in pregnant animals. By point counting, the proportional volume of cardiocytes occupied by granules (V v ) in controls was significantly greater for right than for left appendage (2.12±0.22% vs 1.29±0.16%; mean±SEM;p〈0.05). A significantly similar difference was found for nephrectomy/volume-loaded animals. There was no significant difference inV v for right appendage between the control and experimental groups; for left appendage there was a significant increase inV v to 2.42±0.09% (p〈0.05) for volume-loaded animals only. Estimation of the maximum diameter of granule profiles in control animals was 238±9 nm and 230±6 nm for right and left appendages, respectively. The profile diameters in the left appendages of dehydrated (202±9 nm) and pregnant (200±7 nm) animals were significantly (p〈0.05) less than those of the control animals. The morphometric findings did not correlate with predictions based upon published biochemical data. In the course of this study, a previously unreported bimembranous, circular to ovoid structure was observed in the cardiocyte sarcoplasm of all animals; the nature and function of this structure is unknown.
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  • 2
    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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  • 3
    ISSN: 1432-0878
    Keywords: Key words: Fibroblast growth factor ; Kidney ; Immunohistochemistry ; Glomerulus ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The fibroblast growth factors (FGFs) are a family of conserved polypeptides known to regulate cell differentiation and proliferation. We have used avidin-biotin-enhanced indirect immunohistochemistry to localize FGF-1 and FGF-2 in the rat kidney. The most consistent specific immunostaining pattern is found in paraffin sections from kidneys perfusion-fixed with 4% paraformaldehyde in 0.1 M phosphate buffer. Intracellular immunoreactivity for FGF-1 and FGF-2 is co-localized in visceral (podocytes) and parietal (Bowman’s capsule) glomerular epithelial cells, S3 segments of proximal tubules, distal tubules and collecting ducts in the cortex, and thick ascending limbs and collecting ducts in the medulla. Immunoreactivity is also observed within urothelium and the tunica adventitia of large blood vessels. No immunostaining is found in cortical S1 or S2 segments of proximal tubules, in frozen sections prepared from unfixed or 4% paraformaldehyde perfusion-fixed kidneys, or in paraffin sections from Bouin-fixed kidneys. Immersion fixation with 4% paraformaldehyde gives a similar staining pattern in paraffin sections to that achieved with perfusion fixation. However, in paraffin sections fixed with methyl Carnoy’s fixative, immunoreactivity is primarily localized to the tunica media of blood vessels, with little tubular or glomerular immunostaining. Thus, variation in immunolocalization patterns for FGFs can be partially attributed to differences in fixative, preparative technique and antibody specificity.
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  • 4
    ISSN: 1432-0878
    Keywords: Peripolar cells ; Juxtaglomerular apparatus ; Newborn sheep ; Dexamethasone ; Ultrastructure ; Cytoplasmic granules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the renal juxtaglomerular region of newborn sheep, it was found that glomerular peripolar cells and their granules were very much larger than those found in fetal lambs or adult sheep. Similar peripolar cell hypertrophy was triggered in fetal lambs treated in utero with intraperitoneal injections of dexamethasone. Ultrastructurally, granules of peripolar cells from newborn lambs resembled closely the enlarged zymogen granules described in the pancreas of newborn rats. Such peripolar cell hypertrophy may reflect a functional adaptation of the kidney to immediate postnatal life.
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  • 5
    ISSN: 1432-0878
    Keywords: Peripolar cells ; Juxtaglomerular apparatus ; Kallikrein ; Ultrastructure ; Mammals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Peripolar cells are granulated glomerular epithelial cells that form a cuff around the vascular pole of the glomerulus. Quantitation of these cells in 17 species of mammals (including man, several laboratory animals and a variety of other species) indicated that they were detectable by light microscopy in all but one of the mammals that were examined (the Australian hopping mouse). In adult mammals with detectable peripolar cells, the “peripolar cell index” (the percentage of randomly sectioned glomeruli that displayed peripolar cells in histological sections of kidney) ranged from 0.15 (for echidna) to 11.86 (for sheep). Newborn lambs and rats showed strikingly high values (23.30 and 10.76, respectively) compared with their adult counterparts. Using electron microscopy, peripolar cells were observed in all species that were examined, including the Australian hopping mouse. Morphologically, peripolar cells were similar in all species although their size and granule population varied. They showed a predominantly outer cortical glomerular distribution and a close anatomical relationship with the renin-containing myoepithelioid cells. These findings indicate that peripolar cells are present in a wide variety of species and support the view that such cells may play a significant role in the regulation of normal renal function.
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  • 6
    ISSN: 1432-0878
    Keywords: Transthyretin ; Kidney ; Peripolar cells ; Sheep, newborn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Purified transthyretin has been isolated from sheep serum. Antiserum raised against this protein has been used with an indirect immunoperoxidase histochemical technique to identify transthyretin in newborn lamb kidney tissue. Transthyretin was found in proximal tubule cells and in glomerular peripolar cells. Preabsorption studies using purified transthyretin protein indicate that the immunoreactivity of the antiserum is specific to transthyretin.
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  • 7
    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.
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  • 8
    ISSN: 0003-276X
    Keywords: Development ; Immunohistochemistry ; Renin-containing cells ; Sheep ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: Renin-containing (RC) cells in small ruminant kidneys have been known to be widely distributed along the blood vessels. In the present study, RC cells in developing sheep kidneys were studied to investigate not only the appearance but distribution with the potential physiological significance using immunohistochemical and histophanimetrical techniques.Methods: Seven fetal, 12 newborn, and 3 adult metanephric kidneys were used and immunostained by anti-renin antiserum. In the histoplanimetrical analysis, the numerical values of RC cells existing at the walls of 3 major arterial types in the kidneys were calculated.Results: At day 44 of gestation, RC cells were already demonstrated in the walls of renal, interlobar, and afferent vessels, located in the deep cortex and the medulla. In intermediate gestational periods, RC cells were detected throughout the intrarenal arterial trees. In late gestational periods, RC cells expressed in the walls of interlobar/arcuate and interlobular arteries tended to decrease or disappear gradually, while they were distributed predominantly in the afferent glomerular vessels. In newborn lambs, especially days 1 to 3 after birth, increased numbers of RC cells were demonstrated throughout the arterial trees in the kidneys. In older lambs, RC cells located in the interlobar/arcuate arteries and the proximal region of the interlobular arteries decreased in number and gradually disappeared. Some RC cells were still distributed in the distal portion of the interlobular artery even in the adult sheep.Conclusions: These results suggest that the wide distribution of RC cells in sheep kidney is formed in perinatal life, and that the neuronal regulation is associated with the maintenance of this distribution. © 1994 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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