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Wilhelm Kriz - One of the best experts on this subject based on the ideXlab platform.
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The Vascular Pole of the Renal Glomerulus of Rat - The Vascular Pole of the renal glomerulus of rat.
Advances in Anatomy Embryology and Cell Biology, 1998Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:: In the present study we provide a detailed structural analysis of the Vascular Pole of superficial and midcortical glomeruli of the rat kidney. A description of the juxtaglomerular portions of the afferent and efferent arterioles, the extraglomerular mesangium and the glomerular stalk is included. The specific structural elaboration of the epithelial transition from the podocytes to the parietal epithelium is emphasized, with particular attention to the arrangement of the cytoskeleton and its connections to extracellular matrix elements. The branching patterns of the afferent and efferent arterioles are quite different. Immediately at the glomerular entrance, the afferent arteriole divides into its primary branches. In contrast, the efferent arteriole has a specific outflow segment (consisting of an intraglomerular portion and a portion associated with the extraglomerular mesangium) established by the confluence of capillary tributaries deep inside the glomerular tuft. Just at the transition from inside to outside, this segment includes a prominent narrow portion with conspicuous endothelial cells bulging into the vessel lumen. The extraglomerular mesangium has been found to represent a solid block of cells and matrix filling the space between the macula densa and both arterioles and extending into the entrance funnel. Peripherally located extraglomerular mesangial cells attach to the outer aspect of the parietal basement membrane. As a whole, the extraglomerular mesangium occludes the glomerular tuft. The results appear relevant with respect to four major aspects: (1) a support function counteracting the expansile forces resulting from the high intraglomerular pressures, (2) a direct functional influence of the afferent on the efferent arteriole, resulting from their narrow assemblage at the glomerular entrance, (3) a specific shear stress receptor function of the intraglomerular segment of the efferent arteriole, and (4) fluid leakage from the glomerular tuft through the stalk and the extraglomerular mesangium into the cortical interstitium. 1. The glomerulus is a high-pressure compartment; expansile forces continuously tend to expand glomerular capillaries, the glomerular stalk, and the glomerular entrance. Counteracting centripetal forces at the Vascular Pole appear to be developed as circular forces by the cytoskeleton of podocytes and parietal cells surrounding the glomerular entrance and as interconnecting forces between both arterioles and between opposing walls of the glomerular entrance, as well as of the glomerular stalk. These interconnecting forces are developed by the extraglomerular mesangium which--as a whole--forms a spiderlike closure device holding the glomerular entrance together. In addition, the extraglomerular mesangium develops occluding forces, allowing a gradual pressure drop between the glomerular stalk and the macula densa. 2. At the glomerular entrance, the outflow segment of the efferent arteriole is narrowly associated with the bifurcation of the afferent arteriole. Both are enclosed together in a common compartment surrounded by the glomerular basement membrane; there is no pressure barrier individually encompassing each vessel. Therefore, it may readily be suggested that the hydrostatic pressure of the afferent arteriole acts on the efferent arteriole. As a consequence, the luminal width of the efferent arteriole at this site, i.e., its resistance, may be directly modified by the pressure in the afferent arteriole. 3. The efferent arteriole at the transition of the intraglomerular segment to the segment that passes through the extraglomerular mesangium has a conspicuously narrow portion with endothelial cells protruding into the vessel lumen. In addition, this segment is prominent by the expression of the neuronal type of nitric oxide synthase. We therefore propose that this segment acts as a specific shear stress receptor. The possible relevance of a shear stress receptor at this site would be
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the Vascular Pole of the renal glomerulus of rat
Advances in Anatomy Embryology and Cell Biology, 1998Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:1 Introduction.- 2 Material and Methods.- 3 Results.- 3.1 The Opening in Bowman's Capsulex.- 3.1.1 Transition of the GMB into the PBM.- 3.1.2 Transition from Podocytes to Parietal Cells.- 3.2 Glomerular Arterioles.- 3.2.1 Afferent Arteriole.- 3.2.2 Efferent Arteriole.- 3.3 Extraglomerular Mesangium.- 3.3.1 EGM Cells.- 3.3.2 EGM Matrix.- 3.3.3 EGM Relationships to Neighboring Structures.- 3.3.4 Glomerular Stalk.- 4 Discussion.- 4.1 Stabilization of the Vascular Pole.- 4.2 Regulation of Glomerular Blood Flow and Filtration.- 4.3 Integration of Vascular Pole Structures into the Juxtaglomerular Apparatus.- 4.4 Fluid Leakage Through the Glomerular Stalk.- 5 Summary.- References.
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the Vascular Pole of the renal glomerulus of rat
Advances in Anatomy Embryology and Cell Biology, 1998Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:: In the present study we provide a detailed structural analysis of the Vascular Pole of superficial and midcortical glomeruli of the rat kidney. A description of the juxtaglomerular portions of the afferent and efferent arterioles, the extraglomerular mesangium and the glomerular stalk is included. The specific structural elaboration of the epithelial transition from the podocytes to the parietal epithelium is emphasized, with particular attention to the arrangement of the cytoskeleton and its connections to extracellular matrix elements. The branching patterns of the afferent and efferent arterioles are quite different. Immediately at the glomerular entrance, the afferent arteriole divides into its primary branches. In contrast, the efferent arteriole has a specific outflow segment (consisting of an intraglomerular portion and a portion associated with the extraglomerular mesangium) established by the confluence of capillary tributaries deep inside the glomerular tuft. Just at the transition from inside to outside, this segment includes a prominent narrow portion with conspicuous endothelial cells bulging into the vessel lumen. The extraglomerular mesangium has been found to represent a solid block of cells and matrix filling the space between the macula densa and both arterioles and extending into the entrance funnel. Peripherally located extraglomerular mesangial cells attach to the outer aspect of the parietal basement membrane. As a whole, the extraglomerular mesangium occludes the glomerular tuft. The results appear relevant with respect to four major aspects: (1) a support function counteracting the expansile forces resulting from the high intraglomerular pressures, (2) a direct functional influence of the afferent on the efferent arteriole, resulting from their narrow assemblage at the glomerular entrance, (3) a specific shear stress receptor function of the intraglomerular segment of the efferent arteriole, and (4) fluid leakage from the glomerular tuft through the stalk and the extraglomerular mesangium into the cortical interstitium. 1. The glomerulus is a high-pressure compartment; expansile forces continuously tend to expand glomerular capillaries, the glomerular stalk, and the glomerular entrance. Counteracting centripetal forces at the Vascular Pole appear to be developed as circular forces by the cytoskeleton of podocytes and parietal cells surrounding the glomerular entrance and as interconnecting forces between both arterioles and between opposing walls of the glomerular entrance, as well as of the glomerular stalk. These interconnecting forces are developed by the extraglomerular mesangium which--as a whole--forms a spiderlike closure device holding the glomerular entrance together. In addition, the extraglomerular mesangium develops occluding forces, allowing a gradual pressure drop between the glomerular stalk and the macula densa. 2. At the glomerular entrance, the outflow segment of the efferent arteriole is narrowly associated with the bifurcation of the afferent arteriole. Both are enclosed together in a common compartment surrounded by the glomerular basement membrane; there is no pressure barrier individually encompassing each vessel. Therefore, it may readily be suggested that the hydrostatic pressure of the afferent arteriole acts on the efferent arteriole. As a consequence, the luminal width of the efferent arteriole at this site, i.e., its resistance, may be directly modified by the pressure in the afferent arteriole. 3. The efferent arteriole at the transition of the intraglomerular segment to the segment that passes through the extraglomerular mesangium has a conspicuously narrow portion with endothelial cells protruding into the vessel lumen. In addition, this segment is prominent by the expression of the neuronal type of nitric oxide synthase. We therefore propose that this segment acts as a specific shear stress receptor. The possible relevance of a shear stress receptor at this site would be
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Development of Vascular Pole-associated glomerulosclerosis in the Fawn-hooded rat.
Journal of the American Society of Nephrology : JASN, 1998Co-Authors: Wilhelm Kriz, Hiltraud Hosser, Bruni Hähnel, J L Simons, Abraham P. ProvoostAbstract:Fawn-hooded hypertensive (FHH) rats constitute a spontaneous model of chronic renal failure with early systemic and glomerular hypertension, proteinuria, and development of focal and segmental glomerulosclerosis. The goal of the present study was to elucidate a step-by-step sequence of histopathologic events leading from an initial glomerular injury to segmental sclerosis. Segmental sclerosis in the FHH rat is consistently associated with the glomerular Vascular Pole. The initial injury involves the expansion of primary branches of the afferent arteriole. Apposition of those capillaries to Bowman9s capsule, together with the degeneration and detachment of corresponding podocytes, allows parietal cells to attach to the naked glomerular basement membrane of this capillary, i.e., allows the formation of a tuft adhesion to Bowman9s capsule. The adhesion enlarges to a broad synechia by encroaching to neighboring capillaries, apparently based on progressive podocyte degeneration at the flanks of the adhesion. Capillaries inside the adhesion--before undergoing collapse or hyalinization--appear to stay perfused for some time and to maintain some kind of filtration misdirected toward the cortical interstitium. Thereby, a prominent paraglomerular space comes into existence, enlarging in parallel with the adhesion. Toward the cortical interstitium this space is delimited by a layer of sheetlike fibroblast processes, which has obviously been assembled in response to the formation of this space. Toward the urinary space, the paraglomerular space is demarcated by the parietal epithelium and by the interface between the adhesion and the "intact" tuft remnant. Thus, the sclerotic tuft portions all become enclosed within the paraglomerular space.
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Branching and confluence pattern of glomerular arterioles in the rat.
Kidney International, 1991Co-Authors: D. Winkler, Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:: In addition to the usual division of the glomerular tuft into lobules, a subdivision into an afferent and an efferent capillary domain is made. Immediately after entering the glomerulus the afferent arteriole splits into superficially located branches which supply the lobules. The capillaries of each lobule first run towards the urinary Pole; these parts of each lobule establish the afferent domain. The capillaries of each lobule running back towards the Vascular Pole establish the efferent domain. The afferent domain represents the major part of the tuft; it has the shape of an incomplete globe with a deep depression on one side within which the efferent domain is situated. The efferent arteriole is established inside the glomerular tuft within the efferent capillary domain. Generally tributaries from each lobule converge to form the intraglomerular segment of the efferent arteriole, which leaves the tuft by passing through the mesangium of the glomerular stalk. At this site the intraglomerular segment of the efferent arteriole is fully surrounded by the mesangium; consequently, it is exposed to the intramesangial pressure.
George B.m. Lindop - One of the best experts on this subject based on the ideXlab platform.
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The glomerulo-tubular junction: a target in renal diseases.
The Journal of pathology, 2002Co-Authors: George B.m. Lindop, Ian W. Gibson, Thomas T. Downie, D. Vass, Eric P. CohenAbstract:Both global and segmental glomerulopathies may damage specific areas of the renal glomerulus. Diseases associated with glomerular hyperperfusion cause lesions at the Vascular Pole, while diseases associated with proteinuria often damage the tubular Pole. Atubular glomeruli are now known to be plentiful in a variety of common renal diseases. These glomeruli are disconnected from their tubule at the tubular Pole and therefore cannot participate in the production of urine. It is widely believed that the disconnection is a result of external compression by periglomerular fibrosis. However, the variable anatomy and cell populations within both the glomerulus and the beginning of the proximal tubule at the glomerulo-tubular junction may also have important roles to play in the response to damage at this sensitive site of the nephron.
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Tuft-to-capsule adhesions and their precursors: differences between the Vascular and tubular Poles of the human glomerulus
The Journal of Pathology, 1998Co-Authors: Ian W. Gibson, Thomas T. Downie, Ian A. R. More, George B.m. LindopAbstract:Human glomerular capillary tufts were removed by microdissection and scanning electron microscopy was used to examine the surface of the capillary tuft and the interior of its Bowman's capsule in order to identify connections between the tuft and capsule. Glomeruli were examined in histologically normal renal cortex from 12 kidneys removed for tumour and 12 renal allografts removed for end-stage rejection. In normal kidney, the glomerular tuft was connected to Bowman's capsule by single podocytes and their processes. At the Vascular Pole, these were predominantly associated with parietal podocytes which lined Bowman's capsule. At the tubular Pole, occasional podocytic processes derived from the capillary tuft bridged Bowman's space and connected to Bowman's capsule where there were no parietal podocytes. These podocytic connections were also found in all rejected transplants, but in addition adhesions were identified which consisted of thicker connections between the tuft and capsule. At the Vascular Pole, tuft-to-capsule adhesions were found in all 12 kidneys; these were always associated with parietal podocytes. Tubular Pole adhesions were identified in ten of the 12 transplants. They were associated with abnormal squamous cells, but not with parietal podocytes. When the capillary tuft herniated into the proximal tubule, the tuft sometimes formed an adhesion with the origin of the proximal tubule. These observations suggest that podocyte connections between the glomerular tuft and Bowman's capsule may be precursors of glomerular adhesions at the Vascular Pole. Since tuft-to-capsule adhesions at the Vascular Pole differ morphologically from those at the tubular Pole, this may reflect different pathogenetic mechanisms at the opposite Poles of the glomerulus. © 1998 John Wiley & Sons, Ltd.
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Tuft-to-capsule adhesions and their precursors: differences between the Vascular and tubular Poles of the human glomerulus
The Journal of pathology, 1998Co-Authors: Ian W. Gibson, Thomas T. Downie, Ian A. R. More, George B.m. LindopAbstract:Human glomerular capillary tufts were removed by microdissection and scanning electron microscopy was used to examine the surface of the capillary tuft and the interior of its Bowman's capsule in order to identify connections between the tuft and capsule. Glomeruli were examined in histologically normal renal cortex from 12 kidneys removed for tumour and 12 renal allografts removed for end-stage rejection. In normal kidney, the glomerular tuft was connected to Bowman's capsule by single podocytes and their processes. At the Vascular Pole, these were predominantly associated with parietal podocytes which lined Bowman's capsule. At the tubular Pole, occasional podocytic processes derived from the capillary tuft bridged Bowman's space and connected to Bowman's capsule where there were no parietal podocytes. These podocytic connections were also found in all rejected transplants, but in addition adhesions were identified which consisted of thicker connections between the tuft and capsule. At the Vascular Pole, tuft-to-capsule adhesions were found in all 12 kidneys; these were always associated with parietal podocytes. Tubular Pole adhesions were identified in ten of the 12 transplants. They were associated with abnormal squamous cells, but not with parietal podocytes. When the capillary tuft herniated into the proximal tubule, the tuft sometimes formed an adhesion with the origin of the proximal tubule. These observations suggest that podocyte connections between the glomerular tuft and Bowman's capsule may be precursors of glomerular adhesions at the Vascular Pole. Since tuft-to-capsule adhesions at the Vascular Pole differ morphologically from those at the tubular Pole, this may reflect different pathogenetic mechanisms at the opposite Poles of the glomerulus.
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immune complex deposition in bowman s capsule is associated with parietal podocytes
The Journal of Pathology, 1994Co-Authors: Ian W. Gibson, Thomas T. Downie, I. A. R. More, George B.m. LindopAbstract:We have recently documented the presence of podocytes lining part of Bowman's capsule at the Vascular Pole, in adult human kidney. In this study, we describe the deposition of immune complexes in Bowman's capsule in association with these parietal podocytes. We examined 1 year's consecutive human renal biopsies (n = 170). Transmission electron microscopy (TEM) revealed 18 cases in which parietal podocytes were present. Of these 18, there were 11 cases of glomerulonephritis, in which immune complexes were demonstrated in the capillary tuft by both TEM and direct immunofluorescence microscopy. In seven of these 11 cases, TEM showed immune complex-type deposits in Bowman's capsule, always associated with parietal podocytes. These deposits were similar in size, appearance, and distribution to the deposits in the capillary tuft. By contrast, non-specific electron densities within Bowman's capsule were found beneath both squamous parietal cells and parietal podocytes. In four cases, Bowman's capsule also showed focal positive immunostaining for complement components and/or fibrinogen. Both parietal and visceral podocytes showed similar fusion of pedicles. We suggest that filtration through parietal podocytes may be responsible for immune complex deposition and subsequent damage to the Vascular Pole of the glomerulus in human renal disease.
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A comparative study of the glomerular peripolar cell and the renin-secreting cell in twelve mammalian species.
Cell and tissue research, 1994Co-Authors: Ian W. Gibson, Thomas T. Downie, I. A. R. More, D. S. Gardiner, I. Downie, George B.m. LindopAbstract:The peripolar cell is a glomerular epithelial cell situated within Bowman's capsule at its Vascular Pole. It is believed to be a secretory cell which forms part of the juxtaglomerular apparatus. Scanning electron microscopy was used to perform a comparative study of the morphology and number of peripolar cells in twelve mammalian species. The number of renin-secreting cells in kidney sections stained by renin antibodies and immunocytochemistry was counted. There was a marked inter-species variation in the number, size and appearance of peripolar cells. They were largest and most abundant in sheep and goat and fewest in dog, cow and human. There was no correlation between the numbers of peripolar cells and renin-secreting cells. This does not support the view that the peripolar cell is part of the juxtaglomerular apparatus.
Ian W. Gibson - One of the best experts on this subject based on the ideXlab platform.
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The glomerulo-tubular junction: a target in renal diseases.
The Journal of pathology, 2002Co-Authors: George B.m. Lindop, Ian W. Gibson, Thomas T. Downie, D. Vass, Eric P. CohenAbstract:Both global and segmental glomerulopathies may damage specific areas of the renal glomerulus. Diseases associated with glomerular hyperperfusion cause lesions at the Vascular Pole, while diseases associated with proteinuria often damage the tubular Pole. Atubular glomeruli are now known to be plentiful in a variety of common renal diseases. These glomeruli are disconnected from their tubule at the tubular Pole and therefore cannot participate in the production of urine. It is widely believed that the disconnection is a result of external compression by periglomerular fibrosis. However, the variable anatomy and cell populations within both the glomerulus and the beginning of the proximal tubule at the glomerulo-tubular junction may also have important roles to play in the response to damage at this sensitive site of the nephron.
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Tuft-to-capsule adhesions and their precursors: differences between the Vascular and tubular Poles of the human glomerulus
The Journal of Pathology, 1998Co-Authors: Ian W. Gibson, Thomas T. Downie, Ian A. R. More, George B.m. LindopAbstract:Human glomerular capillary tufts were removed by microdissection and scanning electron microscopy was used to examine the surface of the capillary tuft and the interior of its Bowman's capsule in order to identify connections between the tuft and capsule. Glomeruli were examined in histologically normal renal cortex from 12 kidneys removed for tumour and 12 renal allografts removed for end-stage rejection. In normal kidney, the glomerular tuft was connected to Bowman's capsule by single podocytes and their processes. At the Vascular Pole, these were predominantly associated with parietal podocytes which lined Bowman's capsule. At the tubular Pole, occasional podocytic processes derived from the capillary tuft bridged Bowman's space and connected to Bowman's capsule where there were no parietal podocytes. These podocytic connections were also found in all rejected transplants, but in addition adhesions were identified which consisted of thicker connections between the tuft and capsule. At the Vascular Pole, tuft-to-capsule adhesions were found in all 12 kidneys; these were always associated with parietal podocytes. Tubular Pole adhesions were identified in ten of the 12 transplants. They were associated with abnormal squamous cells, but not with parietal podocytes. When the capillary tuft herniated into the proximal tubule, the tuft sometimes formed an adhesion with the origin of the proximal tubule. These observations suggest that podocyte connections between the glomerular tuft and Bowman's capsule may be precursors of glomerular adhesions at the Vascular Pole. Since tuft-to-capsule adhesions at the Vascular Pole differ morphologically from those at the tubular Pole, this may reflect different pathogenetic mechanisms at the opposite Poles of the glomerulus. © 1998 John Wiley & Sons, Ltd.
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Tuft-to-capsule adhesions and their precursors: differences between the Vascular and tubular Poles of the human glomerulus
The Journal of pathology, 1998Co-Authors: Ian W. Gibson, Thomas T. Downie, Ian A. R. More, George B.m. LindopAbstract:Human glomerular capillary tufts were removed by microdissection and scanning electron microscopy was used to examine the surface of the capillary tuft and the interior of its Bowman's capsule in order to identify connections between the tuft and capsule. Glomeruli were examined in histologically normal renal cortex from 12 kidneys removed for tumour and 12 renal allografts removed for end-stage rejection. In normal kidney, the glomerular tuft was connected to Bowman's capsule by single podocytes and their processes. At the Vascular Pole, these were predominantly associated with parietal podocytes which lined Bowman's capsule. At the tubular Pole, occasional podocytic processes derived from the capillary tuft bridged Bowman's space and connected to Bowman's capsule where there were no parietal podocytes. These podocytic connections were also found in all rejected transplants, but in addition adhesions were identified which consisted of thicker connections between the tuft and capsule. At the Vascular Pole, tuft-to-capsule adhesions were found in all 12 kidneys; these were always associated with parietal podocytes. Tubular Pole adhesions were identified in ten of the 12 transplants. They were associated with abnormal squamous cells, but not with parietal podocytes. When the capillary tuft herniated into the proximal tubule, the tuft sometimes formed an adhesion with the origin of the proximal tubule. These observations suggest that podocyte connections between the glomerular tuft and Bowman's capsule may be precursors of glomerular adhesions at the Vascular Pole. Since tuft-to-capsule adhesions at the Vascular Pole differ morphologically from those at the tubular Pole, this may reflect different pathogenetic mechanisms at the opposite Poles of the glomerulus.
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Scanning electron microscopy of the mammalian renal glomerulus in health and disease
1994Co-Authors: Ian W. GibsonAbstract:The Vascular and tubular Poles of the renal glomerulus are structurally and functionally highly specialised areas. The Vascular Pole forms part of the juxtaglomerular apparatus, involved in the control of renin synthesis and secretion, and it is the site of the peripolar cell, a recently recognised glomerular cell whose function is unknown. In both experimental and human renal disease, lesions can specifically affect the glomerular Vascular Pole (eg. Hilar sclerosis) or tubular Pole (eg. glomerular tip changes). These two sites of glomerular damage reflect different pathogenetic mechanisms. In addition, glomeruli can lose their tubular Pole connection to the rest of the nephron, forming atubular glomeruli. In this study, 1 have used scanning electron microscopy (SEM) to study the glomerular Poles in normal and diseased kidney. To facilitate this, I have developed a new technique of glomerular microdissection, allowing detailed study of the Vascular and tubular Poles of large numbers of glomeruli. The advantages and limitations of this technique are discussed. I have studied the normal Vascular and tubular Poles of the adult human glomerulus. 1 have shown that many glomeruli have parietal podocytes lining Bowman's capsule around the Vascular Pole. The significance of this finding for both normal nephron function and glomerular disease is discussed. I have demonstrated podocytic connections between the glomerular tuft and Bowman's capsule, and detailed the anatomical variations at the human Vascular and tubular Poles. I have performed a species survey of the mammalian glomerular peripolar cell, defining two distinct types of peripolar cell. The dendritic peripolar cell, with a cell body and processes around the arterioles of the Vascular Pole, predominated in rodent species; the globular peripolar cell, with abundant cytoplasmic granules, predominated in the sheep and goat. I have discussed the significance of interspecies variations in peripolar cell numbers and morphology, emphasising the distinctiveness of the peripolar cell as a specific glomerular cell type. I have studied lesions at the Vascular and tubular Poles in human renal allografts. The effect of renal damage on peripolar cells and parietal podocytes was investigated. Structural differences were demonstrated between tuft-to-capsu1e adhesions at the two glomerular Poles. Vascular Pole adhesions were formed by podocytes at areas with parietal podocytes; they may develop from pre-existing normal podocyte connections. In contrast, tubular Pole adhesions did not involve podocytes, and were associated with variable abnormalities in squamous parietal epithelium. The significance of glomerular adhesions, and their underlying pathogenesis, is discussed. Additional varied tubular Pole abnormalities have also been detailed. Finally, I have used SEM to investigate atubular glomeruli in human kidney. I have shown that they are lined extensively by parietal podocytes, they contain contracted capillary tufts, and many form glomerular cysts. I have found that atubular glomeruli are associated with narrowing of the tubular Pole orifice in those glomeruli which retain a tubular connection. The significance of these findings to the pathogenesis of atubular glomeruli, and for filtration within atubular glomeruli, is discussed.
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immune complex deposition in bowman s capsule is associated with parietal podocytes
The Journal of Pathology, 1994Co-Authors: Ian W. Gibson, Thomas T. Downie, I. A. R. More, George B.m. LindopAbstract:We have recently documented the presence of podocytes lining part of Bowman's capsule at the Vascular Pole, in adult human kidney. In this study, we describe the deposition of immune complexes in Bowman's capsule in association with these parietal podocytes. We examined 1 year's consecutive human renal biopsies (n = 170). Transmission electron microscopy (TEM) revealed 18 cases in which parietal podocytes were present. Of these 18, there were 11 cases of glomerulonephritis, in which immune complexes were demonstrated in the capillary tuft by both TEM and direct immunofluorescence microscopy. In seven of these 11 cases, TEM showed immune complex-type deposits in Bowman's capsule, always associated with parietal podocytes. These deposits were similar in size, appearance, and distribution to the deposits in the capillary tuft. By contrast, non-specific electron densities within Bowman's capsule were found beneath both squamous parietal cells and parietal podocytes. In four cases, Bowman's capsule also showed focal positive immunostaining for complement components and/or fibrinogen. Both parietal and visceral podocytes showed similar fusion of pedicles. We suggest that filtration through parietal podocytes may be responsible for immune complex deposition and subsequent damage to the Vascular Pole of the glomerulus in human renal disease.
Marlies Elger - One of the best experts on this subject based on the ideXlab platform.
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The Vascular Pole of the Renal Glomerulus of Rat - The Vascular Pole of the renal glomerulus of rat.
Advances in Anatomy Embryology and Cell Biology, 1998Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:: In the present study we provide a detailed structural analysis of the Vascular Pole of superficial and midcortical glomeruli of the rat kidney. A description of the juxtaglomerular portions of the afferent and efferent arterioles, the extraglomerular mesangium and the glomerular stalk is included. The specific structural elaboration of the epithelial transition from the podocytes to the parietal epithelium is emphasized, with particular attention to the arrangement of the cytoskeleton and its connections to extracellular matrix elements. The branching patterns of the afferent and efferent arterioles are quite different. Immediately at the glomerular entrance, the afferent arteriole divides into its primary branches. In contrast, the efferent arteriole has a specific outflow segment (consisting of an intraglomerular portion and a portion associated with the extraglomerular mesangium) established by the confluence of capillary tributaries deep inside the glomerular tuft. Just at the transition from inside to outside, this segment includes a prominent narrow portion with conspicuous endothelial cells bulging into the vessel lumen. The extraglomerular mesangium has been found to represent a solid block of cells and matrix filling the space between the macula densa and both arterioles and extending into the entrance funnel. Peripherally located extraglomerular mesangial cells attach to the outer aspect of the parietal basement membrane. As a whole, the extraglomerular mesangium occludes the glomerular tuft. The results appear relevant with respect to four major aspects: (1) a support function counteracting the expansile forces resulting from the high intraglomerular pressures, (2) a direct functional influence of the afferent on the efferent arteriole, resulting from their narrow assemblage at the glomerular entrance, (3) a specific shear stress receptor function of the intraglomerular segment of the efferent arteriole, and (4) fluid leakage from the glomerular tuft through the stalk and the extraglomerular mesangium into the cortical interstitium. 1. The glomerulus is a high-pressure compartment; expansile forces continuously tend to expand glomerular capillaries, the glomerular stalk, and the glomerular entrance. Counteracting centripetal forces at the Vascular Pole appear to be developed as circular forces by the cytoskeleton of podocytes and parietal cells surrounding the glomerular entrance and as interconnecting forces between both arterioles and between opposing walls of the glomerular entrance, as well as of the glomerular stalk. These interconnecting forces are developed by the extraglomerular mesangium which--as a whole--forms a spiderlike closure device holding the glomerular entrance together. In addition, the extraglomerular mesangium develops occluding forces, allowing a gradual pressure drop between the glomerular stalk and the macula densa. 2. At the glomerular entrance, the outflow segment of the efferent arteriole is narrowly associated with the bifurcation of the afferent arteriole. Both are enclosed together in a common compartment surrounded by the glomerular basement membrane; there is no pressure barrier individually encompassing each vessel. Therefore, it may readily be suggested that the hydrostatic pressure of the afferent arteriole acts on the efferent arteriole. As a consequence, the luminal width of the efferent arteriole at this site, i.e., its resistance, may be directly modified by the pressure in the afferent arteriole. 3. The efferent arteriole at the transition of the intraglomerular segment to the segment that passes through the extraglomerular mesangium has a conspicuously narrow portion with endothelial cells protruding into the vessel lumen. In addition, this segment is prominent by the expression of the neuronal type of nitric oxide synthase. We therefore propose that this segment acts as a specific shear stress receptor. The possible relevance of a shear stress receptor at this site would be
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the Vascular Pole of the renal glomerulus of rat
Advances in Anatomy Embryology and Cell Biology, 1998Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:1 Introduction.- 2 Material and Methods.- 3 Results.- 3.1 The Opening in Bowman's Capsulex.- 3.1.1 Transition of the GMB into the PBM.- 3.1.2 Transition from Podocytes to Parietal Cells.- 3.2 Glomerular Arterioles.- 3.2.1 Afferent Arteriole.- 3.2.2 Efferent Arteriole.- 3.3 Extraglomerular Mesangium.- 3.3.1 EGM Cells.- 3.3.2 EGM Matrix.- 3.3.3 EGM Relationships to Neighboring Structures.- 3.3.4 Glomerular Stalk.- 4 Discussion.- 4.1 Stabilization of the Vascular Pole.- 4.2 Regulation of Glomerular Blood Flow and Filtration.- 4.3 Integration of Vascular Pole Structures into the Juxtaglomerular Apparatus.- 4.4 Fluid Leakage Through the Glomerular Stalk.- 5 Summary.- References.
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the Vascular Pole of the renal glomerulus of rat
Advances in Anatomy Embryology and Cell Biology, 1998Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:: In the present study we provide a detailed structural analysis of the Vascular Pole of superficial and midcortical glomeruli of the rat kidney. A description of the juxtaglomerular portions of the afferent and efferent arterioles, the extraglomerular mesangium and the glomerular stalk is included. The specific structural elaboration of the epithelial transition from the podocytes to the parietal epithelium is emphasized, with particular attention to the arrangement of the cytoskeleton and its connections to extracellular matrix elements. The branching patterns of the afferent and efferent arterioles are quite different. Immediately at the glomerular entrance, the afferent arteriole divides into its primary branches. In contrast, the efferent arteriole has a specific outflow segment (consisting of an intraglomerular portion and a portion associated with the extraglomerular mesangium) established by the confluence of capillary tributaries deep inside the glomerular tuft. Just at the transition from inside to outside, this segment includes a prominent narrow portion with conspicuous endothelial cells bulging into the vessel lumen. The extraglomerular mesangium has been found to represent a solid block of cells and matrix filling the space between the macula densa and both arterioles and extending into the entrance funnel. Peripherally located extraglomerular mesangial cells attach to the outer aspect of the parietal basement membrane. As a whole, the extraglomerular mesangium occludes the glomerular tuft. The results appear relevant with respect to four major aspects: (1) a support function counteracting the expansile forces resulting from the high intraglomerular pressures, (2) a direct functional influence of the afferent on the efferent arteriole, resulting from their narrow assemblage at the glomerular entrance, (3) a specific shear stress receptor function of the intraglomerular segment of the efferent arteriole, and (4) fluid leakage from the glomerular tuft through the stalk and the extraglomerular mesangium into the cortical interstitium. 1. The glomerulus is a high-pressure compartment; expansile forces continuously tend to expand glomerular capillaries, the glomerular stalk, and the glomerular entrance. Counteracting centripetal forces at the Vascular Pole appear to be developed as circular forces by the cytoskeleton of podocytes and parietal cells surrounding the glomerular entrance and as interconnecting forces between both arterioles and between opposing walls of the glomerular entrance, as well as of the glomerular stalk. These interconnecting forces are developed by the extraglomerular mesangium which--as a whole--forms a spiderlike closure device holding the glomerular entrance together. In addition, the extraglomerular mesangium develops occluding forces, allowing a gradual pressure drop between the glomerular stalk and the macula densa. 2. At the glomerular entrance, the outflow segment of the efferent arteriole is narrowly associated with the bifurcation of the afferent arteriole. Both are enclosed together in a common compartment surrounded by the glomerular basement membrane; there is no pressure barrier individually encompassing each vessel. Therefore, it may readily be suggested that the hydrostatic pressure of the afferent arteriole acts on the efferent arteriole. As a consequence, the luminal width of the efferent arteriole at this site, i.e., its resistance, may be directly modified by the pressure in the afferent arteriole. 3. The efferent arteriole at the transition of the intraglomerular segment to the segment that passes through the extraglomerular mesangium has a conspicuously narrow portion with endothelial cells protruding into the vessel lumen. In addition, this segment is prominent by the expression of the neuronal type of nitric oxide synthase. We therefore propose that this segment acts as a specific shear stress receptor. The possible relevance of a shear stress receptor at this site would be
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Branching and confluence pattern of glomerular arterioles in the rat.
Kidney International, 1991Co-Authors: D. Winkler, Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:: In addition to the usual division of the glomerular tuft into lobules, a subdivision into an afferent and an efferent capillary domain is made. Immediately after entering the glomerulus the afferent arteriole splits into superficially located branches which supply the lobules. The capillaries of each lobule first run towards the urinary Pole; these parts of each lobule establish the afferent domain. The capillaries of each lobule running back towards the Vascular Pole establish the efferent domain. The afferent domain represents the major part of the tuft; it has the shape of an incomplete globe with a deep depression on one side within which the efferent domain is situated. The efferent arteriole is established inside the glomerular tuft within the efferent capillary domain. Generally tributaries from each lobule converge to form the intraglomerular segment of the efferent arteriole, which leaves the tuft by passing through the mesangium of the glomerular stalk. At this site the intraglomerular segment of the efferent arteriole is fully surrounded by the mesangium; consequently, it is exposed to the intramesangial pressure.
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The Vascular Pole of the Renal Glomerulus of Rat - The Vascular Pole of the renal glomerulus of rat.
Advances in Anatomy Embryology and Cell Biology, 1998Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:: In the present study we provide a detailed structural analysis of the Vascular Pole of superficial and midcortical glomeruli of the rat kidney. A description of the juxtaglomerular portions of the afferent and efferent arterioles, the extraglomerular mesangium and the glomerular stalk is included. The specific structural elaboration of the epithelial transition from the podocytes to the parietal epithelium is emphasized, with particular attention to the arrangement of the cytoskeleton and its connections to extracellular matrix elements. The branching patterns of the afferent and efferent arterioles are quite different. Immediately at the glomerular entrance, the afferent arteriole divides into its primary branches. In contrast, the efferent arteriole has a specific outflow segment (consisting of an intraglomerular portion and a portion associated with the extraglomerular mesangium) established by the confluence of capillary tributaries deep inside the glomerular tuft. Just at the transition from inside to outside, this segment includes a prominent narrow portion with conspicuous endothelial cells bulging into the vessel lumen. The extraglomerular mesangium has been found to represent a solid block of cells and matrix filling the space between the macula densa and both arterioles and extending into the entrance funnel. Peripherally located extraglomerular mesangial cells attach to the outer aspect of the parietal basement membrane. As a whole, the extraglomerular mesangium occludes the glomerular tuft. The results appear relevant with respect to four major aspects: (1) a support function counteracting the expansile forces resulting from the high intraglomerular pressures, (2) a direct functional influence of the afferent on the efferent arteriole, resulting from their narrow assemblage at the glomerular entrance, (3) a specific shear stress receptor function of the intraglomerular segment of the efferent arteriole, and (4) fluid leakage from the glomerular tuft through the stalk and the extraglomerular mesangium into the cortical interstitium. 1. The glomerulus is a high-pressure compartment; expansile forces continuously tend to expand glomerular capillaries, the glomerular stalk, and the glomerular entrance. Counteracting centripetal forces at the Vascular Pole appear to be developed as circular forces by the cytoskeleton of podocytes and parietal cells surrounding the glomerular entrance and as interconnecting forces between both arterioles and between opposing walls of the glomerular entrance, as well as of the glomerular stalk. These interconnecting forces are developed by the extraglomerular mesangium which--as a whole--forms a spiderlike closure device holding the glomerular entrance together. In addition, the extraglomerular mesangium develops occluding forces, allowing a gradual pressure drop between the glomerular stalk and the macula densa. 2. At the glomerular entrance, the outflow segment of the efferent arteriole is narrowly associated with the bifurcation of the afferent arteriole. Both are enclosed together in a common compartment surrounded by the glomerular basement membrane; there is no pressure barrier individually encompassing each vessel. Therefore, it may readily be suggested that the hydrostatic pressure of the afferent arteriole acts on the efferent arteriole. As a consequence, the luminal width of the efferent arteriole at this site, i.e., its resistance, may be directly modified by the pressure in the afferent arteriole. 3. The efferent arteriole at the transition of the intraglomerular segment to the segment that passes through the extraglomerular mesangium has a conspicuously narrow portion with endothelial cells protruding into the vessel lumen. In addition, this segment is prominent by the expression of the neuronal type of nitric oxide synthase. We therefore propose that this segment acts as a specific shear stress receptor. The possible relevance of a shear stress receptor at this site would be
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the Vascular Pole of the renal glomerulus of rat
Advances in Anatomy Embryology and Cell Biology, 1998Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:1 Introduction.- 2 Material and Methods.- 3 Results.- 3.1 The Opening in Bowman's Capsulex.- 3.1.1 Transition of the GMB into the PBM.- 3.1.2 Transition from Podocytes to Parietal Cells.- 3.2 Glomerular Arterioles.- 3.2.1 Afferent Arteriole.- 3.2.2 Efferent Arteriole.- 3.3 Extraglomerular Mesangium.- 3.3.1 EGM Cells.- 3.3.2 EGM Matrix.- 3.3.3 EGM Relationships to Neighboring Structures.- 3.3.4 Glomerular Stalk.- 4 Discussion.- 4.1 Stabilization of the Vascular Pole.- 4.2 Regulation of Glomerular Blood Flow and Filtration.- 4.3 Integration of Vascular Pole Structures into the Juxtaglomerular Apparatus.- 4.4 Fluid Leakage Through the Glomerular Stalk.- 5 Summary.- References.
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the Vascular Pole of the renal glomerulus of rat
Advances in Anatomy Embryology and Cell Biology, 1998Co-Authors: Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:: In the present study we provide a detailed structural analysis of the Vascular Pole of superficial and midcortical glomeruli of the rat kidney. A description of the juxtaglomerular portions of the afferent and efferent arterioles, the extraglomerular mesangium and the glomerular stalk is included. The specific structural elaboration of the epithelial transition from the podocytes to the parietal epithelium is emphasized, with particular attention to the arrangement of the cytoskeleton and its connections to extracellular matrix elements. The branching patterns of the afferent and efferent arterioles are quite different. Immediately at the glomerular entrance, the afferent arteriole divides into its primary branches. In contrast, the efferent arteriole has a specific outflow segment (consisting of an intraglomerular portion and a portion associated with the extraglomerular mesangium) established by the confluence of capillary tributaries deep inside the glomerular tuft. Just at the transition from inside to outside, this segment includes a prominent narrow portion with conspicuous endothelial cells bulging into the vessel lumen. The extraglomerular mesangium has been found to represent a solid block of cells and matrix filling the space between the macula densa and both arterioles and extending into the entrance funnel. Peripherally located extraglomerular mesangial cells attach to the outer aspect of the parietal basement membrane. As a whole, the extraglomerular mesangium occludes the glomerular tuft. The results appear relevant with respect to four major aspects: (1) a support function counteracting the expansile forces resulting from the high intraglomerular pressures, (2) a direct functional influence of the afferent on the efferent arteriole, resulting from their narrow assemblage at the glomerular entrance, (3) a specific shear stress receptor function of the intraglomerular segment of the efferent arteriole, and (4) fluid leakage from the glomerular tuft through the stalk and the extraglomerular mesangium into the cortical interstitium. 1. The glomerulus is a high-pressure compartment; expansile forces continuously tend to expand glomerular capillaries, the glomerular stalk, and the glomerular entrance. Counteracting centripetal forces at the Vascular Pole appear to be developed as circular forces by the cytoskeleton of podocytes and parietal cells surrounding the glomerular entrance and as interconnecting forces between both arterioles and between opposing walls of the glomerular entrance, as well as of the glomerular stalk. These interconnecting forces are developed by the extraglomerular mesangium which--as a whole--forms a spiderlike closure device holding the glomerular entrance together. In addition, the extraglomerular mesangium develops occluding forces, allowing a gradual pressure drop between the glomerular stalk and the macula densa. 2. At the glomerular entrance, the outflow segment of the efferent arteriole is narrowly associated with the bifurcation of the afferent arteriole. Both are enclosed together in a common compartment surrounded by the glomerular basement membrane; there is no pressure barrier individually encompassing each vessel. Therefore, it may readily be suggested that the hydrostatic pressure of the afferent arteriole acts on the efferent arteriole. As a consequence, the luminal width of the efferent arteriole at this site, i.e., its resistance, may be directly modified by the pressure in the afferent arteriole. 3. The efferent arteriole at the transition of the intraglomerular segment to the segment that passes through the extraglomerular mesangium has a conspicuously narrow portion with endothelial cells protruding into the vessel lumen. In addition, this segment is prominent by the expression of the neuronal type of nitric oxide synthase. We therefore propose that this segment acts as a specific shear stress receptor. The possible relevance of a shear stress receptor at this site would be
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Three-dimensional analysis of the whole mesangium in the rat.
Kidney international, 1996Co-Authors: Kazue Inkyo-hayasaka, Tatsuo Sakai, Naoto Kobayashi, Isao Shirato, Yasuhiko TominoAbstract:Three-dimensional analysis of the whole mesangium in the rat. The three-dimensional structure of the mesangium was analyzed by means of reconstruction from serial semithin and ultrathin sections of the rat glomerulus. The mesangial domains traced on light micrographs of semithin sections were transferred to styrene models, which were stacked up to reconstruct the whole mesangium. The reconstructed mesangium was tree-like in shape and was divided into three lobes that were connected to the Vascular Pole by a slender neck. The glomerulus contained no islets of mesangium which were not connected to the Vascular Pole. The mesangium contained 64 mesangial loops that were penetrated by capillaries. Reliability of the findings on the mesangial loops was ascertained by various methods including reconstruction of part of the mesangium from ultrathin sections. Electron microscopic observations revealed that the arms of the mesangial loops were frequently very slender and consisted of mesangial cell processes containing prominent bundles of actin filaments. The mesangial loops were distributed evenly within the mesangium. Considering previous reports showing about 400 capillary branches in the rat glomerulus as well as the present findings, we concluded that the mesangial loops may change the distribution of intraglomerular blood flow by dynamic contraction of the mesangial cells, or serve as an additional safety device to prevent the expansion of glomerular capillaries.
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Branching and confluence pattern of glomerular arterioles in the rat.
Kidney International, 1991Co-Authors: D. Winkler, Marlies Elger, Tatsuo Sakai, Wilhelm KrizAbstract:: In addition to the usual division of the glomerular tuft into lobules, a subdivision into an afferent and an efferent capillary domain is made. Immediately after entering the glomerulus the afferent arteriole splits into superficially located branches which supply the lobules. The capillaries of each lobule first run towards the urinary Pole; these parts of each lobule establish the afferent domain. The capillaries of each lobule running back towards the Vascular Pole establish the efferent domain. The afferent domain represents the major part of the tuft; it has the shape of an incomplete globe with a deep depression on one side within which the efferent domain is situated. The efferent arteriole is established inside the glomerular tuft within the efferent capillary domain. Generally tributaries from each lobule converge to form the intraglomerular segment of the efferent arteriole, which leaves the tuft by passing through the mesangium of the glomerular stalk. At this site the intraglomerular segment of the efferent arteriole is fully surrounded by the mesangium; consequently, it is exposed to the intramesangial pressure.
