Figure 1.

Major steps in heart development. Diagrams of developing hearts (ventral views) are shown. At the cardiac crescent stage, the two heart fields represent different cardiac precursors. The first heart field (FHF, pink) contributes to the left ventricle (lv), and the second heart field (SHF, blue) contributes to the right ventricle (rv) and later to the outflow tract (ot), sinus venosus (sv), and left and right atria (la and ra, respectively). Days of development for mouse and human are shown below. (From Bruneau 2008, with permission.)