Which cells produce the myelin sheath in the peripheral nervous system?

Which cells produce the myelin sheath in the peripheral nervous system?

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

Answer: (A)

In the peripheral nervous system, the cells that create the myelin sheath are Schwann cells. They wrap around a nerve fiber to form a myelin layer, which acts as insulation and speeds up signal transmission through saltatory conduction. Each Schwann cell covers a single segment of one axon, with gaps between segments known as nodes of Ranvier that help the signal jump quickly along the fiber. This is different from the central nervous system, where oligodendrocytes produce myelin and can extend their processes to wrap many axons or many segments of different axons. Astrocytes and microglia have other roles—astrocytes support neuronal health and maintain the environment, while microglia are immune cells of the CNS. Since the question asks about the peripheral nervous system, Schwann cells are the correct answer.

In the peripheral nervous system, the cells that create the myelin sheath are Schwann cells. They wrap around a nerve fiber to form a myelin layer, which acts as insulation and speeds up signal transmission through saltatory conduction. Each Schwann cell covers a single segment of one axon, with gaps between segments known as nodes of Ranvier that help the signal jump quickly along the fiber. This is different from the central nervous system, where oligodendrocytes produce myelin and can extend their processes to wrap many axons or many segments of different axons. Astrocytes and microglia have other roles—astrocytes support neuronal health and maintain the environment, while microglia are immune cells of the CNS. Since the question asks about the peripheral nervous system, Schwann cells are the correct answer.