Fig. 1. Expression of Hh pathway components in whole-mount Xenopus embryos. Whole-mount in situ hybridisation on stage 41 embryos using probes as indicated. For each probe a lateral view and a dorsal view are shown. A Gli3 sense probe has been used in A,B. Expression of X-bhh and X-chh in the retina is restricted to the RPE (black arrowheads in C,E). X-chh is also expressed in the hindbrain (white arrowhead in E). In addition to a strong expression in the brain, some expression in the retina can be detected for X-shh, X-Smo, Gli2 and Gli3 (arrowheads in H,N,R,T). Although a strong expression in the brain can be detected, expression of X-Ptc-1, X-Ptc-2 and Gli1 in the retina at this stage is very weak (I-L,O-P). Anterior is towards the right. Scale bar: 300 µm.