What cells are responsible for the myelination of nerve fibers in the PNS?

The myelination of nerve fibers in the peripheral nervous system (PNS) is primarily carried out by Schwann cells. These glial cells wrap around the axons of neurons in the PNS, forming the myelin sheath that insulates the nerve fibers. This insulation is crucial for the rapid transmission of electrical impulses along the axons. Each Schwann cell can myelinate one segment of a single axon, and the multiple Schwann cells along the length of an axon contribute to the formation of a continuous myelin sheath.

In contrast, oligodendrocytes are the cells responsible for myelination in the central nervous system (CNS), where a single oligodendrocyte can extend its processes to myelinate multiple axons. Microglia serve as the immune cells in the CNS, playing a role in inflammation and repair, while astrocytes provide structural support and help maintain the blood-brain barrier, but are not involved in the myelination process. Understanding these distinct roles of glial cells enhances comprehension of how both the PNS and CNS maintain their functions, particularly in relation to nerve signal transmission.