The relationship between microglia and brain macrophages. Experimental investigations.

A series of experiments are reported which indicate that the microglia are endogenous cells which may constitute the only source of phagocytes in certain mild degenerative conditions, such as Wallerian degeneration and retrograde nerve cell disintegration. In more extensive lesions with increased vascular permeability a substantial number of the phagocytes are derived from the blood monocytes.