Microglia consists of cells which are resident macrophages of the brain and spinal cord, thus forming the main immune system in the central nervous system.
These small cells are mobile are capable of phagocytosis. They derive from the hematopoietic marrow. Their cytoplasm can be visualized by silver staining. Functionally, they are very plastic, capable of structural changes based on their location and necessity. They can function as scavenger cells, phagocytic, repair promoters, and homeostatic maintenance.
Microglial Cell (Lower Right)
Cerebral Cortex Magnification 60X
Courtesy of Thomas W.Smith, MD; Department of Pathology, University of Massachusetts Medical School. 97803
Microglial cells can proliferate when lesions occur in the CNS. They become antigen presenting cells. They also secrete cytokines, proteins and free radicals that can, sometimes, aggravate injuries.
Essentially, they protect the CNS from bacterial, viral, parasitic infections, as well as tumor prevention. However, they also play a role in chronic inflammation and neurodegeneration, in diseases such as Alzheimer’s and Parkinson’s.