Fig. 4.
The Crx>Math5 BAC transgene is expressed at low levels in proliferative retinal progenitors. E15.5 Crx>Math5 BAC; R26floxGFP embryos were pulsed with EdU for 1 hr and costained for the indicated markers. (A) Projection images of 10 µm optical sections show that all Cre+ cells were EdU− indicating that Cre is not expressed at high levels during S-phase. (B) In contrast, many GFP+ stripes contain EdU+ cells (arrows, inset), consistent with stochastic Cre expression in proliferating RPCs. (C) A small number of Brn3b+ RGCs were identified among clustered GFP+ cells (arrow, inset). Scale bar, 50 µm.
