Math5 defines the ganglion cell competence state in a subpopulation of retinal progenitor cells exiting the cell cycle

► Math5 bHLH factor confers ganglion cell competence on retinal progenitor cells. ► Math5 is expressed in neurogenic cells during terminal G2 phase or early G0. ► Quantitative Math5>Cre lineage analysis and birthdating in wildtype and mutant mice. ► Identification of Math5-independent ganglion cells. ► Math5 does not actively determine non-RGC fates.