AAMC FL Practice Exam

What type of cells produce myelin in the peripheral nervous system (PNS)?

1. Oligodendrocytes

2. Astrocytes

3. Schwann cells

4. Microglia

The correct answer is: Schwann cells

Myelin in the peripheral nervous system (PNS) is produced by Schwann cells. These specialized glial cells wrap around the axons of neurons in the PNS, creating a myelin sheath that insulates the axons and enhances the speed of electrical impulses along the nerve. The process of myelination is critical for efficient signal transmission, and each Schwann cell is responsible for myelinating a single segment of an axon. In contrast, oligodendrocytes are the cells responsible for producing myelin in the central nervous system (CNS). Astrocytes serve various supportive functions in both the CNS and PNS, including maintaining the blood-brain barrier and providing metabolic support to neurons, but they do not produce myelin. Microglia are the immune cells of the CNS, playing a role in the immune response and maintaining homeostasis, but they are not involved in myelination. Understanding the specific roles of these different types of cells helps in grasping the overall function and structure of the nervous system.