The heart is one of the most important organs in the human body. It is responsible for circulating blood and oxygen throughout the body, which is essential for maintaining life. During embryonic development, the heart forms early in gestation and continues to develop and mature until birth. This article will review the stages of embryonic heart development and the cellular mechanisms involved.
Embryonic heart development begins during the fourth week of gestation and proceeds until birth. During this time, the heart tube initially forms, followed by the septation and looping of the heart tube to form the four chambers of the heart. Additionally, the coronary arteries that supply the heart with oxygenated blood develop, as do the major cardiac veins that return deoxygenated blood to the heart.
The first step in heart development is the formation of the heart tube. This occurs through the fusion of the left and right cardiogenic mesoderm, which are the regions of the primitive streak that give rise to cardiomyocytes. During this process, the cardiac crescent, a crescent-shaped region of cardiomyocytes, forms and then expands to form the heart tube. This heart tube is composed of three layers, the endocardium, myocardium, and epicardium.
Once the heart tube is formed, looping and septation begin. This process involves the folding of the heart tube in a counterclockwise direction to form a loop. Septation then occurs in the loop, with the formation of the atrioventricular septum and the interventricular septum. These two septa divide the heart tube into the four chambers of the heart, the right and left atria, and the right and left ventricles.
The coronary arteries are essential for supplying the heart with oxygenated blood. During embryonic heart development, the coronary arteries form from the aortic arches, which are a series of paired arteries that arise from the aortic sac. The aortic arches give rise to both the systemic and pulmonary circulation. The right and left coronary arteries form from the fourth aortic arch, and they branch off from the aorta to supply the heart with oxygenated blood.
The cardiac veins are responsible for returning deoxygenated blood to the heart. During embryonic heart development, the major cardiac veins form, including the right and left anterior cardinal veins, the posterior cardinal veins, and the common cardinal vein. These veins bring deoxygenated blood from various organs to the heart.
Embryonic heart development is a complex process that begins during the fourth week of gestation and continues until birth. During this time, the heart tube forms, followed by the looping and septation of the heart tube to form the four chambers of the heart. The coronary arteries then develop, followed by the formation of the major cardiac veins. All of these processes are essential for the development and maturation of the heart.