Cardiovascular System Development
The cardiovascular system is composed of the blood vessels (arteries, veins, and capillaries), blood, and heart and functions to provide oxygen to and remove waste from tissues and organs. Underscoring its physiological significance, the cardiovascular system is the first to develop during organogenesis when simple diffusion can no longer support the growing embryo. The cardiovascular system arises from the mesoderm layer as paired bilateral structures that migrate to the ventral midline and fuse. Cardiac morphogenesis of the fused heart tube includes heart looping, chamber formation, septation, and cardiomyocyte differentiation to allow for functional blood flow. Blood cells, derived via hematopoiesis, are pumped from the heart through the vessels that develop during the process of vasculogenesis. During the somite stages of embryogenesis, vasculogenesis forms the primary blood vessels, which are later expanded, remodeled, and pruned during angiogenesis.