Neurolemma

Neurolemma (also neurilemma and sheath of Schwann) is the outermost layer of nerve fibers in the peripheral nervous system. It is a nucleated cytoplasmic layer of Schwann cells that surrounds the myelin sheath of axons.

Unlike the axon and the myelin sheath, the neurolemma does not degenerate after a nerve has been cut or crushed; the hollow tube formed by the neurolemma is instrumental in regenerating the nerve fiber