Quick Facts
A basement membrane is a thin sheet of amorphous extracellular material upon which the basal surfaces of epithelial cells rest; other cells associated with basement membranes are muscle cells, Schwann cells, and fat cells. The membrane is interposed between the cellular elements and the underlying connective tissue. It usually comprises two layers, the basal lamina and the reticular lamina, and is composed of Type IV collagen (which is unique to basement membranes), laminin, fibronectin, and heparan sulfate proteoglycans (Dorland, 2011).
Related parts of the anatomy
Structure and/or Key Feature(s)
The basement membrane of the glomerulus is a 300–370 nm thick basal lamina produced by both the endothelial cells of the fenestrated capillaries and the podocytes (or cells of the visceral layer of the glomerular capsule). Its mesh-like structure consists of type IV collagen, laminin, nidogen, and entactin, as well as heparan sulfate proteoglycans and multi-adhesive glycoproteins (Ross and Pawlina, 2006).
Anatomical Relations
The basement membrane of the glomerulus is an interface between the endothelial cells of the fenestrated capillaries and the podocytes.
Function
The basement membrane of the glomerulus is one of three components of the glomerular filtration barrier or filtration apparatus. The other two components are the fenestrated endothelium of the glomerular capillaries and the visceral layer (podocytes) of the glomerular (Bowman’s) capsule.
Clinical Correlates
—Mutation in genes coding components of the type IV collagen cause Alport’s syndrome (hereditary glomerulonephritis) which shows red cells and significant amounts of protein in the urine and progressive renal failure.
—Collagen type IV is also the target of autoimmune diseases.
References
Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.
Ross, M. H. and Pawlina, W. (2006) Histology: A text and atlas. Lippincott Williams & Wilkins.
