Schematic presentation of the glomerular basement membrane structure.
The glomerular basement membrane (GBM) is a specialized basal lamina, formed at the boundary between epithelial podocytes and endothelial cells.
Podocytes anchored to the GBM have extending foot processes that interdigitate to form a slit diaphragm, a unique type of tight junction.
The endothelial cells of the glomerular capillary tuft are fenestrated (with pores), thus providing access of plasma solutes to the GBM and slit diaphragm.
Together, the fenestrated endothelium, GBM, and slit-diaphrgam make up the glomerular filter and function to retain high molecular weight proteins and blood cells in the circulation, while allowing small molecules, such as water, sugars, and electrolytes, to enter the nephron.