This portion of Figure 10-6A from Developmental Stages in Human Embryos shows an outline of the myocardial mantle and endocardial tube at the plexiform phase of cardiac development.
	Key: * left interventricular sulcus. Ao.1, aortic arch 1. C-T, conotruncus. RV, right ventricle. LV, left ventricle. RA, right atrium. LA, left atrium.