原始心脏的形成 Neural groove Neural groove Foregut First aortic First aortic arcl Bulbus cordis Amnion Picard Bulboventricular Cardiac jelly sulcus Pericard cavity Endocardium Atrioventricular Primative Vitelline vein Septum atrium Yolk sac. transversum Left horn Yo%k sac of sinus venosus day:原始心脏的形成