Final answer:
Oligodendrocytes produce myelin in the CNS, and Schwann cells produce myelin in the PNS. Glial cells have supportive roles and various functions in the nervous system.
Step-by-step explanation:
Oligodendrocytes are glial cells that produce myelin in the central nervous system (CNS), while Schwann cells produce myelin in the peripheral nervous system (PNS). Glial cells, also known as neuroglia, play a supportive role to neurons and have multiple functions in the nervous system. In addition to myelin production, astrocytes provide nutrients and support, microglia scavenge pathogens and dead cells, and ependymal cells produce cerebrospinal fluid. Glial cells are vital for the functioning of the nervous system.