1. "Podocytes (or visceral epithelial cells ) are cells of the visceral epithelium in the kidneys[1] 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 macromolecules such as serum albumin and gamma globulin remain in the bloodstream. Small molecules such as water, glucose, and ionic salts are able to pass through the slit diaphragms and form an ultrafiltrate[2] which is further processed by the nephron to 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." (1)