Fig. 1. Cyp26a1, Rarg and Raldh2 expression in wild-type and mutant embryos. Comparative views of E9.0 wild-type (WT) embryos, after hybridization with Cyp26a1 (A,B) and Rarg (C,D) riboprobes. Profile views (A,C) and detail of the caudal region (B,D). Note the differential extent of both types of transcripts, Rarg extending more rostrally than Cyp26a1 in both mesodermal (me) and neurectodermal (ne) tissues. (E,F) Rarg transcript distribution in E9.0 wild-type (E) and Cyp26a1^-/- (F) embryos. Although the overall Rarg expression level may be decreased (e.g. in the first branchial arches, b1), its spatial distribution does not appear to be altered in the mutant. (G,H) Raldh2 exhibits comparable transcript distributions in E8.0 wild-type (G) and Rarg^-/- (H) embryos. b1, first branchial arch; ht, heart; so, somites; tb, tail bud.