What are the primary myelin-forming cells in the peripheral nervous system?

The primary myelin-forming cells in the peripheral nervous system are Schwann cells. These cells play a crucial role in the formation of the myelin sheath, which surrounds axons of peripheral neurons, facilitating faster transmission of electrical signals. Schwann cells wrap around a segment of an axon, creating multiple layers of myelin that insulate the axon, thereby improving signal conduction speed and efficiency.

In contrast, oligodendrocytes are responsible for myelin formation in the central nervous system. Astrocytes are supportive cells that perform various roles, including maintaining the blood-brain barrier and providing metabolic support to neurons, but they do not form myelin. Microglia serve as the immune cells of the central nervous system, helping to protect against pathogens and clear debris, but they also do not contribute to myelination.