27.9 : Basal Lamina are the Specialized Form of ECM

The basal lamina is a thin extracellular layer that lies underneath the cells and separates them from other tissues. The three layers of the basal lamina are lamina lucida, lamina densa and lamina reticularis. The basal lamina, a mixture of glycoproteins and collagen, provides an attachment site for the epithelium, separating it from underlying connective tissue. The framework of basal lamina has other essential proteins such as laminins mesh, perlecan, entactin, and type IV collagen.

Proteins like integrins and dystroglycan in the cell membranes attach to proteins like laminins and fibronectin in the basal lamina, associating the cell with the extracellular matrix of the connective tissue. The basal lamina present in the kidney, serves as a molecular filter, whereas, at the neuromuscular junction, it surrounds the muscle cells, separating them from the nerve cells at the synapse. The basal lamina further helps regenerate the synapse after an injury and aids in localizing acetylcholine receptors.