Fig. 6. Deficient Hh activity results in abnormal DM development and reduced cell motility. Mef2C-AHF-Cre; Smo^flox/-;R26R mutant embryos and controls are compared. β-galactosidase staining at E10.5 (A,B) demonstrates relatively normal DM levels in mutant (B). Staining at E11.5 (C,D) demonstrates loss of DMP (asterisk) while some atrial myocardial and PAS staining is maintained. (E-H) Lysotracker Red cell death analysis demonstrates no detectable increase in mutant embryos (F,H) when compared with controls (E,G) at E10.5 or E11.5. (I,J) Sagittal sections stained for MF-20 (red) and nuclei (green) demonstrate normal myocardial staining in the DMP and absence of MF-20 staining in DM in E11.5 wild type (I) compared with abnormal MF-20 staining within the DM of Mef2C-AHF-Cre; Smo^flox/- embryos (J). MF-20 channel only (I',J') shows ectopic staining. (K) Significantly decreased DM migration is observed with 10 µm cyclopamine treatment compared with media alone or DMSO controls. A, atria; IAVC, inferior atrioventricular cushion; PAS, primary atrial septum; RV, right ventricle; SAVC, superior atrioventricular cushion. ^*P=0.02 (media versus cyclopamine), ^*P=0.001 (DMSO versus cyclopamine).