Figure 1.

The developing heart tube. During embryogenesis the SHF contributes to the arterial pole which includes the great arteries and the right ventricle from the AHF. From the PHF, second heart field cells enter the venous pole. The myocardium and intrapericardial part of the aorta are covered by epicardial cells that are provided by a proepicardial organ of the vPEO and aPEO, respectively. Not shown in this figure: neural crest cells migrate from the neural tube primarily to the arterial pole of the heart [adapted from Grewal et al. 2014 (5)]. SHF, second heart field; AHF, anterior population; PHF, posterior heart field; vPEO, venous pole; aPEO, arterial pole.