Change Of The Second Heart Field And Cardiac Neural Crest In Cx43 Knockout Mouse Embryo

Objective:To investigate the cardiac development defects in Cx43 knockout mouse embryos and the migration and differentiation of progenitor cells of the second heart field?SHF?and cardiac neural crest?CNC?.Methods:In this study,serial sections of Cx43 gene knockout homozygous(Cx43^-/-)mouse and Cx43 wild-type(Cx43^+/+)mouse embryos from Embryonic day 10?ED10?to ED13 were performed immunohistochemical and immunofluorescent double staining,and 3D reconstruction.Results:1.In Cx43 gene knockout mouse embryos at ED10^ED11,Isl1 positive SHF cells in the ventral mesenchyme of the foregut extended through the area between the bilateral arch arteries to the dorsal wall of pericardial cavity.Meanwhile,Isl1 positive cells in the core mesenchyme of the branchial arches were continuous with those in the dorsal wall of pericardial cavity and the distal wall of the outflow tract.At ED13,the distribution of Isl1 positive cells was observed in the wall of the ascending aorta and pulmonary trunk as well as the wall of the left and right outflow tract of the septated ventricles.However,comparing with wild-type mouse embryos,less Isl1 positive SHF cells were shown in Cx43 gene knockout mouse embryos?P<0.01?.2.During ED10 to ED11,Ap2?positive neural crest cells were still found in the wall of the arch artery and the dorsal and ventral walls of the aortic sac in Cx43 gene knockout mouse embryos,but the number of these cells was less than that of wild-type mouse embryos?P<0.01?.Conclusion:1.The results indicate that the migration route and distribution pattern of Isl1 positive SHF cells and Ap2?positive CNC cells are similar between the Cx43 gene knockout and wild-type mouse embryos,but the number of migrating cells is reduced after Cx43gene knockout.2.The data suggests that besides CNC derived cells,the decrease of SHF progenitor cells might involve in the formation of the outflow tract defects in Cx43 knockout mouse embryos.