Fig. 5. Hedgehog signals acting through Smoothened induce Vax gene expression. Anterior is to the left in the lateral views (A-H,J,K) and anterior is to the top in the dorsal views (I,L) of 24 hpf brains showing expression of genes (indicated bottom right) in wild-type (WT) (A-C,I), shh-injected wild-type (WT+shh) (D-F,L) embryos, smoothened^-/- (smu) (G,H), and shh-injected smoothened^-/- (smu+shh) (J,K) mutant embryos. In shh-injected wild-type embryos, expression of the ventral retinal gene, vax2, expands dorsally (E), whereas expression of the dorsal retinal gene, tbx5, is abolished (F). Abbreviations: cf, choroid fissure; dr, dorsal retina; nr, nasal retina; tr, temporal retina.