Fig. 5From: Functiogenesis of cardiac pacemaker activityRepresentation of events in generation of spontaneous rhythmic electrical activity (i.e., pacemaking function) in early phases of cardiogenesis of chick embryo. The ventral views of the chick embryos in 6- to 9-somite stages are shown on the left. aHamburger and Hamilton [H–H, Ref. 10]Back to article page