Fig. 1.
Deletion of Smoothened from the SHF results in severe cardiac abnormalities. A: To specifically delete Smoothened from the second heart field, male Mef2c-AHF-cre;Smoflox/+ mice were mated to female Smoflox/flox mice to generate Mef2c-AHF-cre;Smoflox/flox (SHF-Smofl/fl) mice. D–G: Histological analysis of SHF-Smofl/fl ckos at ED14.5 and beyond revealed a wide spectrum of congenital heart defects. B,C: While control embryos showed proper atrioventricular septation with a well-developed DMP-derived inferior rim (arrows), the majority of SHF-Smofl/fl ckos were found to have an ostium primum atrial septal defects, (asterisk in D,E) with a common AV valve orifice. F,G: The embryos also displayed severe outflow abnormalities, including persistent truncus arteriosus, right descending aorta, and retroesophageal subclavian arteries. cAVvalve, common AV valve; DMP, dorsal mesenchymal protrusion; LDA, left descending aorta; RDA, right descending aorta; PTA, persistent truncus arteriosus; RV, right ventricle; LV, left ventricle; reSA, retroesophageal subclavian artery; RA, right atrium; LA, left atrium; PuV, pulmonary vein; pAS, primary atrial septum; AVSD, atrioventricular septal defect