Talk in general about myelin

Myelin is synthesized by two types of specialized glial cells (myelinating or myelinogenic cells): oligodendrocytes in the CNS and Schwann cells in the PNS; it is arranged around large-caliber axons of the central and peripheral nervous systems. Myelin is a good electrical insulator and allows the rapid spreading of the action potential along the nerve fiber; in the fresh state it appears white and refractive