What type of glial cell is primarily responsible for producing the myelin sheath in the central nervous system?

The glial cell primarily responsible for producing the myelin sheath in the central nervous system is the oligodendrocyte. Oligodendrocytes play a critical role in the insulation of neuronal axons, which is essential for the efficient transmission of electrical signals between nerve cells. The myelin sheath formed by oligodendrocytes allows for faster conduction of action potentials through a process called saltatory conduction, where the impulses jump between the nodes of Ranvier instead of traveling continuously along the axon.

In contrast, microglial cells are involved in the immune defense of the central nervous system, acting as resident macrophages to respond to injury and disease. Astrocytes have various functions, including supporting neuronal health, regulating blood flow, and maintaining the extracellular environment, but they do not form myelin. Ependymal cells line the ventricles of the brain and are involved in the production and circulation of cerebrospinal fluid. Understanding the specific functions of these different types of glial cells highlights the unique roles that contribute to overall brain health and function.