Radial glia regulate Cajal-Retzius cell positioning in the early embryonic cerebral cortex

► Detachment of radial glial endfeet results in C-R cell displacement from the pia. ► C-R cell displacement is not due to BM, meningeal, or cell autonomous defects. ► C-R cell displacement is temporally preceded by disruptions in radial glial scaffold. ► Ablation of radial glia similarly results in local displacement of C-R cells.