The basal membrane is an extra-cellular matrix lining an epithelium and separating it from the underlying connective tissue. It varies in thickness from 50 to 800 nanometres. It is found connected to all epithelia (skin, digestive tract, bladder, uterus, etc.).
The basal membrane has several roles. It is used as the anchoring point for the epithelium and is essential to healing. It protects the underlying tissues and offers permeability to different molecules, particularly nutrients.
Electron microscopy reaveals that the basal membrane looks like two different layers, the basal lamina, and the reticulated lamina.