Fig. 4.

Podocyte and foot processes: key components of the slit diaphragm. The healthy glomerular epithelial cell, or “podocyte,” surrounds the glomerular capillaries and faces the urinary space; the podocyte has numerous branching projections that terminate in numerous, interdigitating foot processes maintained by a dynamic actin cytoskeleton; the interface between individual foot processes forms the slit diaphragm, which acts as a selective barrier through which glomerular filtrate passes but albumin is normally excluded. Loss of foot process architecture is associated with albuminuria. CB, cell body; MP, major (or primary) process; SP, secondary process; FP, foot process.