Fig. 6. BMPR-IA is required for dorsal/ventral patterning of the hindlimb. (A,C,E,G) Wild type; (B,D,F,H) mutant. (A-D) Lmx1b expression was restricted to dorsal mesoderm in normal 11.5 dpc hindlimb (A). However, the mutant hindlimbs demonstrated a double dorsal phenotype with Lmx1b expression being detected in ventral mesoderm (B; arrowhead). Lmx1b expression in the mutant forelimb (D) was indistinguishable from the control forelimb (C). (E) Wnt7a expression was normally restricted to the dorsal ectoderm of the limb field/bud in a normal 10.25 dpc embryo. (F) Wnt7a expression was expanded into the ventral region of the limb field/bud in the Bmpr conditional mutants. (G) En1 expression was restricted to the ventral region of the limb field/bud in a normal 10.25 dpc embryo, which is necessary to suppress Wnt7a expression in this region. (H) En1 expression was almost completely lost in the Bmpr conditional mutant. Arrow indicates region where En1 gene expression should normally exist.