Phenotypic analyses of conditional knockout Smo mutant GTs. (A) β-gal staining on cross-section or sagittal section (inset) of an E12.5 Msx2-rtTA;tetO-Cre;R26R/+ GT (Dox treatment at E9.5) showing strong Cre expression in UE and mesenchyme, especially the dorsal GT mesenchyme. (B,C) SEM analysis of E15.5 male UEMes-Smo-cKO (C) and littermate control (B) GT. (D,E) H&E staining of UEMes-Smo-cKO (E) and littermate control (D) GT. The planes of sections are indicated in B and C (dashed lines). (F) β-gal staining on cross-sections of a E12.5 ShhCregfp/+;R26R/+ GT demonstrating Cre expression in UE. (G-J) SEM and histological analyses of UE-Smo-cKOs (H,J) and littermate controls (G,I). (K) β-gal staining on cross-sections of a E10.5 Dermo1-Cre;R26R/+ GT showing that the expression was exclusively in the cloacal mesenchyme. (L-N) Light microscopy of Mes-Smo-cKOs (M,N) and control (L). GTs from E15.5 male mouse embryos were analyzed in B-E,G-J,L-N.