Name = Podocyte
Caption = Glomerulus. (Diagram in French, but "Membrane basale glomerulaire et ses
podocytes" labeled near center.)
Dorlands = six/000084389
DorlandsID = Podocyte |
Podocytes (or visceral epithelial cells ) are cells of the visceral
epitheliumin the kidneys[DorlandsDict|six/000084389|Podocyte] and form a crucial component of the glomerular filtration barrier, contributing size selectivity and maintaining a massive filtration surface.
Adjacent podocytes interdigitate to cover the basal lamina which is intimately associated with the
glomerular capillaries, but the podocytes leave gaps or thin filtration slits.
The slits are covered by slit diaphragms which are composed of a number of cell-surface proteins including
nephrin, podocalyxin, and P-cadherin, which ensure that large macromoleculessuch as serum albuminand gamma globulinremain in the bloodstream.
Small molecules such as
water, glucose, and ionic salts are able to pass through the slit diaphragms and form an ultrafiltrate[eMedicineDictionary| Podocyte] which is further processed by the nephronto produce urine.
Podocytes are also involved in regulation of
glomerular filtration rate(GFR). When podocytes contract, they cause closure of filtration slits. This decreases the GFR by reducing the surface area available for filtration.
Structural features of podocytes indicate a high rate of vesicular traffic in these cells. Many coated vesicles and coated pits can be seen along the basolateral domain of the podocytes.
In their cell bodies, podocytes possess a well-developed
endoplasmic reticulumand a large Golgi apparatus, indicative of a high capacity for protein synthesisand post-translational modifications.
"Pedicels" (or "foot processes") extend from the podocyte and increase the surface area. [GeorgiaPhysiology|7/7ch04/7ch04p08]
Disruption of the slit diaphragms or destruction of the podocytes can lead to massive
proteinuriawhere large amounts of protein are lost from the blood.
An example of this occurs in the congenital disorder
Finnish-type nephrosis, which is characterised by neonatal proteinuria leading to end-stage renal failure. This disease has been found to be caused by a mutation in the nephringene.
* [http://www.georgetown.edu/users/acp34/images/Podocyte.jpgScanning-electron micrograph of a podocyte] , from
* - "Mammal, renal vasculature (EM, High)
* - ". Ultrastructure of the Cell: podocytes and glomerular capillaries"
* [http://www.podocyte.ca/ podocyte.ca] at
Samuel Lunenfeld Research Institute
Wikimedia Foundation. 2010.