Cardiac Crescent

The cardiac crescent is formed by the cranially bilateral heart fields fusion at the midline (in mammals) before somite and heart tube formation which populate both endocardial and myocardial progenitors. As the two limbs of the cardiac crescent begin to fuse, a pair of endocardial tubes develop within each limb. As the limbs of the cardiac crescent join, these tubes coalesce to form the primitive heart tube.