RA signaling is altered in the dorsal neuroretina of Lrp6-KO embryos at embryonic day (E) 10.5. A,C: Raldh1 mRNA is expressed in the dorsal neuroretina of normal control embryos. B,D: Expression of Raldh1 mRNA is nearly absent in the mutant eyes. E,G: Raldh3 mRNA is expressed in both dorsal eye cup (arrows) and ventral retina (arrowheads) in the wild-type embryos. F: Raldh3 mRNA expression domain in the ventral retina shifts dorsally in the mutant eyes (arrowheads). H: Raldh3 mRNA expression is decreased in dorsal retinal pigment epithelium (RPE; arrow). Note the altered Raldh3 expression pattern in orofacial region (asterisks in G,H) of the mutants. Axes: a, anterior; p, posterior; d, dorsal; v, ventral; l, lateral; m, medial. Scale bars = 100 μm.