A tissue-resident macrophage found in the central nervous system.
This extended description was generated by ChatGPT and reviewed by the CellGuide team, who added references, and by the CL editors, who approved it for inclusion in CL. It may contain information that applies only to some subtypes and species, and so should not be considered definitional. Central Nervous System (CNS) macrophages represent an integral part of the brain's innate immune system. These immune cells play crucial roles in maintenance and regulation, homeostasis, and disease response, thereby helping in the overall cognitive functioning of an organism. There are different macrophage populations in the CNS, often classified into microglial cells, which reside in the parenchyma, and non-parenchymal macrophages at the interface between the brain and the periphery, including the perivascular spaces, the choroid plexus, and the meninges. CNS macrophages are derived from erythromyeloid progenitors in the yolk sac. CNS macrophages have distinct morphologies: Meningeal and perivascular macrophages have a more elongated shape than microglia, which are characterized by a small cell body with fine processes; in contrast, choroid plexus macrophages typically have a stellate shape. Microglia are the most abundant abundant mononuclear phagocytes and have been shown to play a number of physiological roles, including proinflammatory and anti-inflammatory functions, synaptic pruning and remodeling, and apoptotic cell removal through phagocytosis. Non-parenchymal CAMs primarily support the barrier function against external antigens. Meningeal macrophages have been shown to respond to peripheral microbial challenges and to protect the brain against fatal viral infection. CNS macrophages are also involved in the initiation and progression of many neurological diseases, such as Alzheimer's disease and Parkinson's disease as well as multiple sclerosis.