Sox4 and Sox11 deletion during earliest retinal development demonstrates requirement for RGC differentiation in vivo. A–C, Control, Chx10-Cre/Sox4fl/fl, Chx10-Cre/Sox11fl/fl, and Chx10-Cre/Sox4fl/fl/Sox11fl/fl retinal explants were immunostained for the RGC markers RBPMS (green) and Brn3+ (red). There was a similar decrease in RGCs detected in Chx10-Cre/Sox4fl/fl or Chx10-Cre/Sox11fl/fl mice, and a near complete loss of RGCs in the Chx10-Cre/Sox4fl/fl/Sox11fl/fl mice. D, Eye sections of Cre-negative or Cre-expressing mice from E14 and E18 were immunostained for Cre recombinase (green) and Brn3 (red). Magnified images from E14 retina are shown as insets. Scale bars: A, 30 μm; D, 100 μm (*p < 0.05; **p < 0.01 by Student's t test).