define schwann cells
Schwann cell in Medicine Expand. Schwann cell (shwÃ¤n, shvÃ¤n) n. Any of the cells that cover the nerve fibers in the peripheral nervous system and form the myelin sheath. Also called neurilemma cell. Schwann cell. Any of the cells that cover the axons in the peripheral nervous system and form the myelin sheath. See more at myelin.