Myelin sheath is produced by

Oligodendrocytes are neuroglial cells which produce myelin sheath in the central nervous system while Schwann cell produces myelin sheath in the peripheral nervous system. Myelin is an insulating layer or sheath that forms around nerves, including those in the brain and spinal cord. It is made up of protein and fatty substances. This myelin sheath allows electrical impulses to transmit quickly and efficiently along the nerve cells.