Figure 5

Ectopic Bmp signaling in the epithelia of the URS in the E9.5-TM-treated β-catenin GOF mutants. Sagittal sections of the embryos at E13.5 (a–h). The expression of Bmp4 and Bmp7 was increased in the mutant URS epithelium (e and f). Msx2, a downstream target of Bmp signaling, and pSmad1/5/8 were ectopically induced (g and h). The red arrowheads indicate ectopic induction of the gene and protein expression (e–h). Sagittal sections of the wild-type, Shh^CreERT2/+; β-catenin^flox(ex3)/+, Shh^CreERT2/+; β-catenin^flox(ex3)/+; BmprIA^flox/− embryos at E18.5 subsequent to E9.5-TM treatment (i–k). Ventral view of a Shh^CreERT2/+; β-catenin^flox(ex3)/+; BmprIA^flox/− embryo (k′). The URS abnormality was partly restored in the Shh^CreERT2/+; β-catenin^flox(ex3)/+; BmprIA^flox/− mutants compared with that observed in the Shh^CreERT2/+; β-catenin^flox(ex3)/+ mutants (j and k). The blue arrowhead indicates the tip of the URS. gt, genital tubercle; r, rectum; t, tail; u, urethra; urs, urorectal septum