Foot processes of podocytes interdigitate with one another forming filtration slits (or slit pores) that, in contrast to those in the glomerular endothelium

Endothelium

The endothelium is the thin layer of cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. These cells are called endothelial cells. Endothelial cells line the entire circulatory system, from the heart...

, are spanned by slit diaphragms.

Structure

Some studies suggest that the size of the filtration slits restricts the passage of large molecules (eg, serum albumin

Serum albumin

Serum albumin, often referred to simply as albumin is a protein that in humans is encoded by the ALB gene.Serum albumin is the most abundant plasma protein in mammals. Albumin is essential for maintaining the osmotic pressure needed for proper distribution of body fluids between intravascular...

) and cells (eg, red blood cell

Red blood cell

Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...

s and platelet

Platelet

Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes.  The average lifespan of a platelet is normally just 5 to 9 days...

s). Proteins that are required for the correct function of the slit diaphragm include nephrin

Nephrin

Nephrin is a protein necessary for the proper functioning of the renal filtration barrier. The renal filtration barrier consists of fenestrated endothelial cells, the glomerular basement membrane, and the podocytes of epithelial cells...

, NEPH1

KIRREL

Kin of IRRE-like protein 1 is a protein that in humans is encoded by the KIRREL gene.-Interactions:KIRREL has been shown to interact with Nephrin and Tight junction protein 1.-Further reading:...

, NEPH2

KIRREL3

Kin of IRRE-like protein 3 also known as nin of irregular chiasm-like protein 3 or nephrin-like protein 2 is a protein that in humans is encoded by the KIRREL3 gene....

, podocin

Podocin

Podocin is a protein component of the slit diaphragm of podocytes. Glomerular capillary endothelial cells, the glomerular basement membrane and the slit diaphragms function as the filtration barrier of the kidney glomerulus....

, and CD2AP

CD2AP

CD2-associated protein is a protein that in humans is encoded by the CD2AP gene.-Interactions:CD2AP has been shown to interact with NPHS2, Nephrin, Cbl gene and RAB4A.-Further reading:...

.