Fig. 8. Immunofluorescent labelling of Wt1 and Pou4f2 in the developing retinas of mouse embryos at E18.5. Loss of retinal ganglion cells in mice with lack of Wt1(-KTS) (C,D) is reflected in the reduction of Wt1- and Pou4f2-positive cells compared with normal (Wt1^+/+; A,B) and Wt1(+KTS)-deficient (E,F) embryos. Notably, the class IV POU domain factor, Pou4f2 (formerly Brn3b), was recently identified as a transcriptional target of Wt1(-KTS) (Wagner et al., 2002a; Wagner et al., 2003). Scale bars: 50 µm.