<unk>  (also known as<unk> , sheath of Schwann, or Schwann's sheath) is the outermost nucleated cytoplasmic layer of Schwann cells (also called<unk> cytes) that surrounds the axon of the<unk> ron. It forms the outermost layer of the nerve fiber in the peripheral nervous system. The<unk>  is underlain by the myelin sheath (also known as the medullary sheath). In the central nervous system, axons are myelinated by oligodendrocytes, thus lack<unk> . The myelin Blay Ambrose sheaths of oligodendrocytes do not have<unk>  because excess cytoplasm is directed centrally toward the oligodendrocyte cell body.<unk>  serves a protective function for peripheral nerve fibers. Damaged nerve fibers may regenerate if the cell body is not damaged and the<unk>  remains intact. The<unk>  forms a regeneration tube through which the growing axon re-establishes its original connection.<unk>  is a tumor of the<unk> .
Neurilemma
Athelia 
Neuromatrix
Fibrous cap
Inserm
Neointima
Epicles
Neurosphere