Summary CARDIOVASCULAR SYSTEM DEVELOPMENT

Development of Cardiovascular System • The cardiovascular system consists of the heart and blood vessels. • They are mesodermal in origin with significant contributions made by neural crest cells. • Development begins at the middle of the third week, when the embryo is no longer able to satisfy its nutritional requirements by diffusion alone. • Progenitor heart cells lie in the epiblast, immediately adjacent to the cranial end of the primitive streak. • From there, they migrate through the streak and into the splanchnic layer of lateral plate mesoderm Cardiogenic Field • Cranial to the neural folds, the progenitor cells form cluster of cells called the cardiogenic field that transforms to a horseshoe-shaped endothelial lined tube called primary heart field (PHF) surrounded by myoblasts during days 16 to 18. • The cells that will become the atria and the ventricles are specified on both sides from lateral to medial • The secondary heart field appears slightly later (days 20 to 21) • Once cells establish the heart fields, they are induced by the underlying pharyngeal endoderm to form blood islands that forms blood cells and vessels by the process of vasculogenesis and angiogenesis