Advances in the Second Heart Field

Abstract : The deployment of progenitor cells from the second heart field (SHF) to the poles of the cardiac tube drives heart tube elongation during looping morphogenesis. Defects in this process underlie a spectrum of common forms of congenital heart defects (CHDs) affecting the cardiac poles, including conotruncal and atrioventricular septal defects. In this chapter recent findings will be reviewed concerning sequential steps in SHF development: the early emergence of the SHF lineage, the epithelial properties of SHF cells during heart tube elongation, and the importance of the transition zone as progenitor cells differentiate at the cardiac poles. Together these studies define critical regulatory nodes at successive stages of SHF deployment, providing new insights into mechanisms of heart development and the origins of CHD.