What type of cells are microglia primarily classified as?

Microglia are primarily classified as macrophages due to their role in the immune response within the central nervous system. These cells originate from yolk sac progenitors and are part of the mononuclear phagocyte system. Their primary function is to act as the main form of active immune defense in the brain and spinal cord. Microglia continuously monitor the environment for signs of injury or disease, and upon activation, they can change shape, proliferate, and phagocytose cellular debris, pathogens, and dead neurons.

This classification as macrophages is significant because microglia share several functional properties with peripheral macrophages, including the ability to process and present antigens and secrete cytokines, which help regulate inflammatory responses. Understanding microglia in this context is crucial for studying neuroinflammatory conditions, neurodegenerative diseases, and other neurological disorders, where their function can significantly influence disease outcomes.

Other cell types listed, such as neurons, astrocytes, and oligodendrocytes, have distinct roles within the nervous system, primarily related to neurotransmission, supporting neuronal health, and myelination, respectively, but do not function as immune cells.