medical Definition of basal lamina
1
: the part of the gray matter of the embryonic neural tube from which the motor nerve roots arise
2
: a thin extracellular layer composed chiefly of collagen, proteoglycans, and glycoproteins (as laminin and fibronectin) that lies adjacent to the basal surface of epithelial cells or surrounds individual muscle, fat, and Schwann cells and that separates these cells from underlying or surrounding connective tissue or adjacent cells — compare reticular lamina
