Which glial cells form the myelin sheath in the peripheral nervous system?

Which glial cells form the myelin sheath in the peripheral nervous system?

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

Answer: (A)

Schwann cells are the glial cells that form the myelin sheath in the peripheral nervous system. They wrap their membranes around a single axon segment, creating the insulating layers that speed up nerve impulses through saltatory conduction. Each Schwann cell myelinates one portion of an axon, with gaps between segments called nodes of Ranvier where voltage-gated channels boost conduction. In contrast, oligodendrocytes in the central nervous system can extend processes to myelinate multiple axons. Astrocytes support neurons and maintain the extracellular environment, while microglia act as immune cells. Some small peripheral fibers remain unmyelinated but are still associated with a Schwann cell, which provides a protective sheath without a thick myelin layer.

Schwann cells are the glial cells that form the myelin sheath in the peripheral nervous system. They wrap their membranes around a single axon segment, creating the insulating layers that speed up nerve impulses through saltatory conduction. Each Schwann cell myelinates one portion of an axon, with gaps between segments called nodes of Ranvier where voltage-gated channels boost conduction. In contrast, oligodendrocytes in the central nervous system can extend processes to myelinate multiple axons. Astrocytes support neurons and maintain the extracellular environment, while microglia act as immune cells. Some small peripheral fibers remain unmyelinated but are still associated with a Schwann cell, which provides a protective sheath without a thick myelin layer.