Which cell type forms myelin in the peripheral nervous system?

• A. Schwann cells
• B. Astrocytes
• C. Oligodendrocytes
• D. Neurons

Answer: (A)

The key idea here is identifying which glial cell creates the myelin sheath in the peripheral nervous system. In the peripheral nervous system, Schwann cells perform myelination. A single Schwann cell wraps around a segment of one axon, forming the insulating myelin sheath that increases conduction speed via saltatory conduction. This is different from the brain and spinal cord, where oligodendrocytes produce myelin and can extend their processes to myelinate multiple axons. Astrocytes support neurons and maintain the extracellular environment but do not form myelin, and neurons themselves are the signaling cells rather than the myelinating cells.