20 μm retinal cryosections from mice injected with EdU at the ages indicated and sacrificed 4 hours later were immunostained with the antibodies indicated, following EdU visualization. A: EdU labeled RPCs at E12, E14, E16, and P0 do not express Isl2. B: Tbr2 is not expressed by progenitor cells at E14, E16 or P0. C: Satb2 is not expressed by progenitor cells at P0. NBL, neuroblast layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer. For all three transcription factors, no cellular colocalization with Edu label was observed: n=3-5 animals/age, 5-7 sections/animal examined. Scale bars, 50 μm.