The beta astrocyte: its possible role as a central nervous system phagocyte

Phagocytic cells in the normal ageing mouse brain have the structural characteristics of the cells described by Reyners et al. (1982) as beta astrocytes and are quite different from microglial cells. Like the beta astrocyte (Reyners et al. 1986) they remain mitotically active even in extreme old age. Phagocytic cells in the immature mouse central nervous system contain glycogen but no microfilaments and may be immature beta astrocytes. A re-examination of the literature indicates that many phagocytes previously unidentified or considered to be microglial cells are probably beta astrocytes.