Fig. 4. Expression pattern of Raldh3 during Xenopus development. (A) Raldh3 expression as detected by whole-mount in situ hybridization of whole embryos (stage 10.25-31) or dissected neural retinas, without lens and pigmented epithelium (stage 59). cf, choroid fissure. Scale bar: 350 µm. (B) Raldh3 expression in transverse sections of stage 33 embryos after whole-mount in situ hybridization. From left to right, sections show expression at progressively posterior levels. op, olfactory placode; os, optic stalk. (C) Comparison of Pax2, Raldh3 and Vax2 expression in the optic cup in transversal sections of stage 33 embryos after whole-mount in situ hybridization. (D) Double in situ hybridizations of Rx1 with Raldh2, Shh or FGF8 on mid- to late neurula embryos shown from anterior view. The inset shows a double in situ hybridization of Rx1 with FGF8 on an early neurula embryo.