base·ment membrane .bā-smənt- n
1) a thin extracellular supporting layer that separates a layer of epithelial cells from the underlying lamina propria and is composed of the basal lamina and reticular lamina
2) basal lamina
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the thin delicate membrane that lies at the base of an epithelium. It is composed of mucopolysaccharide and fibres of protein.
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a 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, fat cells, and capillaries. The membrane is interposed between the cellular elements and the underlying connective tissue. It 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.
Basement membrane, comprising the lamina lucida and lamina densa, which together constitute the basal lamina, and the collagen-containing reticular lamina beneath, in a diagram of a section through epithelial tissue.
Medical dictionary. 2011.