The neurolemma is underlain by the basal lamina (referred to as the medullary sheath in the included illustrations). In the CNS, axons are myelinated by oligodendrocytes, thus lack neurolemma. The myelin sheaths of Oligodendrocytes do not have neurolemma because excess cytoplasm is directed centrally toward the Oligodendrocyte cell body.
Neurolemma serves a protective function for peripheral nerve fibers. Damaged nerve fibers may regenerate if the perikaryon is not damaged and the neurolemma remains intact. The neurolemma forms a regeneration tube through which the growing axon reestablishes its original connection.