The primary heart field

• Heart development starts with cardiac progenitor cells formation
• Cardiac progenitor cells are derived from intraembryonic mesoderm that emerged from the cranial third of the primitive streak during gastrulation.
• endoderm, ectoderm and midline mesoderm induce the cardiac progenitor cells to migrate in a cranial-lateral direction to become localized on either side of the primitive streak
• Cardiac progenitor cells form a horseshoe-shaped callded cardiac crescent within the extraembryonic splanchnic mesoderm,
• Cardiogenic cells within the cardiac crescent constitute the primary heart field
• The cardiogenic cells of the primary heart field eventually form the left ventricle and the atria