Intraglomerular mesangial cell

Overview
Intraglomerular mesangial cells are specialized pericytes located among the glomerular capillaries within a renal corpuscle.

There are three primary functions of intraglomerular mesangial cells: filtration, structural support, and phagocytosis.

Filtration and structure
Glomerular capillaries consist of endothelial cells with large fenestrations, and are therefore very permeable ("leaky") for most solutes in blood plasma.

They provide structural support for and regulate blood flow of the glomerular capillaries by their contractile activity.

They are also major contributors to the extracellular matrix which contains fibronectin, type IV collagen, perlecan, and laminin.

Phagocytosis
Mesangial cells also phagocytose glomerular basal lamina components and immunoglobulins.