fig1

Figure 1. *These markers and/or genes have been described in detail mostly in preclinical mouse models as described in this review. Origins and specific cellular markers and genes of microglia and macrophages. (A) Schematic summarizing the embryonic origins of microglia and macrophages from the yolk sac (YS) and fetal liver, respectively; (B) YS macrophages migrate to the central nervous system (CNS) early in embryonic development and remain in the brain as tissue resident macrophages, or microglia. Fetal liver and bone marrow hematopoietic stem cells (HSCs) mature into monocytes and enter the peripheral blood^[13]; and (C) during states of CNS inflammation, particularly in the context of glioblastoma (GBM) tumor microenvironment (TME), microglia and macrophages experience shifts in phenotype; the underlying genetic changes are schematically represented here to show pro-tumor or anti-tumor associated genes^[12]. In reality, there are most likely microglial and macrophage populations that have concurrent expression of anti-tumor and pro-tumor genes