Depending on the location, different glial cell types make myelin in a different manner. Schwann cells make myelin in the peripheral nervous system (PNS: nerves) and oligodendrocytes in the central nervous system (CNS: brain and spinal cord). In the PNS, one Schwann cell forms a single myelin sheath (Figure 1A).he nervous system is comprised of two primary cell types: neurons and glial cells. These cells communicate with each other to perform important tasks in the nervous system. The glial cells support neurons structurally and maintain their long-term neuronal integrity, and neurons regulate glial cell behavior.