The schematic representation shows the stage specific main cardiac morphogens and molecular markers composing the regulatory signaling pathways of cardiomyocyte formation (commitment, specification, differentiation) during heart development. From left, cardiac crescent formation through mesoderm-derived cardiac progenitor activation, consisting of the first heart field (FHF) and second heart field (SHF) cardiac progenitors. Following is the linear heart tube formation and cardiomyocyte progenitors appearance and sequentially heart looping with initiation of chamber formation that ultimate with the formation of the septated heart. The last stage of the adult heart coincides with cardiomyocyte terminal differentiation.