Osmosis video - Development of the cardiovascular system

The cardiovascular system develops at the beginning of week three during prenatal life. The development of the primitive heart starts with a horseshoe-shaped structure called the primary heart field, which has a pair of tubes that fold so that the heart structures will be in the proper position. Next, septa appear, which help to partition the heart into two atria and two ventricles.

The electrical conduction system of the primitive heart initially lies in the sinus venosus. As the sinus venous becomes absorbed by the right atria, the pacemaker cells appear in the sinoatrial node in the right atrium wall. The development of blood vessels involves the endothelium, which undergoes a process called angiogenesis, which is the formation of new blood vessels from pre-existing ones. This process is driven by growth factors such as VEGF (vascular endothelial growth factor).