Radial glia promote microglial development through integrin αβ -TGFβ1 signaling.

Microglia diversity emerges from interactions between intrinsic genetic programs and environment-derived signals, but how these processes unfold and interact in the developing brain remains unclear. Here, we show that radial glia-expressed integrin beta 8 (ITGB8) expressed in radial glia progenitors activates microglia-expressed TGFβ1, permitting microglial development. Domain-restricted deletion of in these progenitors establishes complementary regions with developmentally arrested "dysmature" microglia that persist into adulthood.