In peripheral nerves, the axons are enveloped by which supporting cells?

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

Answer: (A)

In peripheral nerves, axons are enveloped by Schwann cells. These glial cells wrap around the axon to form the myelin sheath, which insulates the nerve fiber and speeds conduction of impulses. Each Schwann cell myelinates a single segment of one axon in the peripheral nervous system, though a single cell can wrap tightly around that segment multiple times.

Oligodendrocytes, by contrast, perform a similar role in the central nervous system, where one oligodendrocyte can myelinate multiple axons. Astrocytes provide structural and metabolic support in the CNS, not the PNS. Microglia are immune-related cells in the CNS. Hence, the correct cellular envelope in peripheral nerves is Schwann cells.