Kidney nontumor

Topic Completed: 1 March 2012

Minor changes: 1 October 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Kidney glomeruli [title]

Nikhil Sangle, M.D.
Page views in 2019: 2,139
Page views in 2020 to date: 828
Cite this page: Sangle N. Glomeruli. website. Accessed June 1st, 2020.
Definition / general
  • Tuft-like vascular structure composed of lobules of specialized capillaries that arise from an afferent arteriole and eventually coalesce to drain into an efferent arteriole
  • 200 microns in diameter, 20% larger in juxtamedullary area
  • Layers (inner to outer) are: fenestrated endothelium, then glomerular basement membrane (lamina rare interna, lamina densa and lamina rare externa), then podocytes (visceral epithelium with foot processes); also parietal epithelium which lines Bowman space (which contains the ultrafiltrate of plasma)
  • Glomerular basement membrane (GBM): normally 250 - 380 nm, composed of type IV collagen, laminin, polyanionic proteoglycans (mostly heparan sulfate), fibronectin and entactin
  • Type IV collagen forms suprastructure to which other glycoproteins attach; composed of 3 alpha chains
  • Each alpha chain has amino 7S domain, middle triple helical domain and a carboxyl noncollagenous (NC1) domain; NC1 domain is site of anti-GBM nephritis and dimer formation
  • Mesangial cells: type of myofibroblast that supports glomerular tuft, regulates capillary width and blood flow; are phagocytic and can proliferate; the mesangium on the capillary side is covered by endothelial cell; the capillary basement membrane extends to form the paramesangial basement membrane; at ultrastructural level, the mesangium shows cell membrane dense bodies (attachment plaques), which anchors the mesangial cell to the cell membrane
  • Podocytes (visceral epithelium): their foot processes embed in lamina rare externa of glomerular basement membrane; the distal diffusion barrier to filtration of proteins is a filtration slit diaphragm between foot processes
Glomerular filtration
  • Glomeruli are highly permeable to water and solutes through fenestrated endothelium; they are impermeable to large proteins like albumin (proteins are more permeable if smaller and more cationic)
Diagrams / tables

Images hosted on other servers:

Normal glomerulus

Vessels surrounding glomeruli and tubules

Microscopic (histologic) description
  • Hypercellularity: the presence of more than 3 cells in an individual glomerular mesangial region away from the vascular pole
Microscopic (histologic) images

Images hosted on other servers:

Various images of normal glomeruli

Special stains
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