MICROANATOMY

Detailed explanation-1: -The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often incorrectly referred to as the basement membrane, though it does constitute a portion of the basement membrane.

Detailed explanation-2: -The basal lamina consists of a mixture of collagens, laminin (glycoprotein), perlecan (heparan sulphate glycoprotein), entactin (glycoprotein). These proteins can bind to each other to make a highly crosslinked extracellular matrix as shown in this diagram.

Detailed explanation-3: -The key difference between basal lamina and basement membrane is that basal lamina is composed of two layers while basement membrane is composed of three layers. Epithelial cells are tightly bound into sheets called epithelia. The extracellular matrix is small and thin and underlies the epithelium.