Scanning Electron Microscopy of the Mammalian Renal Glomerulus in Health and Disease

Gibson, Ian W (1994) Scanning Electron Microscopy of the Mammalian Renal Glomerulus in Health and Disease. MD thesis, University of Glasgow.

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Abstract

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.

Item Type: Thesis (MD)
Qualification Level: Doctoral
Additional Information: Adviser: G B M Lindop
Keywords: Medicine, Morphology
Date of Award: 1994
Depositing User: Enlighten Team
Unique ID: glathesis:1994-74727
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 27 Sep 2019 16:57
Last Modified: 27 Sep 2019 16:57
URI: http://theses.gla.ac.uk/id/eprint/74727

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