Which of the following glial cells acts as a phagocyte in the central nervous system?

Microglial cells serve as the primary immune defense in the central nervous system and function as phagocytes. They play a critical role in maintaining homeostasis, modulating inflammation, and responding to injury or disease. When there is cellular debris, pathogens, or damaged cells, microglia can become activated and migrate to the site of injury. They engulf and digest these unwanted materials through a process called phagocytosis, thus helping to protect neuronal health and promote recovery after injury.

Other glial cells, such as ependymal cells, oligodendrocytes, and astrocytes, have distinct functions. Ependymal cells line the ventricles of the brain and help produce and circulate cerebrospinal fluid. Oligodendrocytes are responsible for forming the myelin sheath around axons, which enhances the speed of electrical impulses in the nervous system. Astrocytes provide structural support, maintain the blood-brain barrier, and regulate nutrient and ion balance, but they do not specialize in phagocytosis. Therefore, microglial cells are the key glial cell type that acts as phagocytes within the central nervous system.