The heart's journey from a simple tube to a complex four-chambered organ is a marvel of embryonic development. This process, occurring in the first eight weeks of pregnancy, involves intricate folding, looping, and to create distinct chambers and vessels.
After birth, the fetal heart undergoes crucial changes to adapt to life outside the womb. Fetal shunts close, allowing for separate pulmonary and systemic circulations. The coronary system develops fully, ensuring proper blood supply to the heart muscle itself.
Embryonic Heart Development and Fetal Heart Anatomy
Stages of embryonic heart development
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forms heart tubes
arise from cardiogenic mesoderm and fuse to form a single heart tube (day 22)
Heart tube elongates and loops
Elongation and looping of the heart tube establishes left-right asymmetry (day 23-28)
contributes to the positioning of the developing heart
Septa form to divide heart into four chambers
develops to divide the into left and right atria
forms to divide the into left and right ventricles
separates the atria from the ventricles (day 28-56)
develop into valves and septa
Tricuspid and mitral valves form between the atria and ventricles from
Aortic and pulmonary valves develop at the bases of the great arteries from (day 35-56)
, an extracellular matrix, plays a crucial role in cushion formation
Outflow tract divides into aorta and pulmonary artery
separates the into the ascending aorta and pulmonary trunk (day 28-56)
Coronary vasculature develops from epicardium
Coronary arteries and veins form from epicardial cells and connect to the aorta and right atrium, respectively (day 56-birth)
Regions of fetal and adult heart
Develops into the left and right atria, which receive blood from the lungs and body, respectively
Primitive ventricle
Develops into the left and right ventricles, which pump blood to the body and lungs, respectively
Develops into the outflow tracts, including the ascending aorta and pulmonary artery
Contributes to the formation of the right atrium and sinoatrial node, the heart's pacemaker
Truncus arteriosus
Divides into the ascending aorta, which supplies the body, and the pulmonary trunk, which supplies the lungs
Fetal shunt between the right and left atria that allows oxygenated blood to bypass the lungs; closes after birth
Fetal shunt between the pulmonary artery and aorta that diverts blood away from the lungs; closes after birth
Transformation of fetal to adult cardiac anatomy
Atrial and ventricular septa formation
and fuse to divide the primitive atrium into left and right atria
Muscular and membranous portions of the fuse to divide the primitive ventricle into left and right ventricles
Valve formation from endocardial cushions
Tricuspid and mitral valves develop from atrioventricular cushions and regulate blood flow between the atria and ventricles
Aortic and pulmonary valves develop from outflow tract cushions and regulate blood flow into the aorta and pulmonary artery
Outflow tract septation
Aorticopulmonary septum divides the truncus arteriosus into the ascending aorta and pulmonary artery, separating systemic and pulmonary circulation
Closure of fetal shunts
Foramen ovale closes to separate the left and right atria, preventing mixing of oxygenated and deoxygenated blood
constricts and becomes the , a fibrous remnant connecting the aorta and pulmonary artery
Coronary circulation development
Coronary arteries and veins form from epicardial cells and connect to the aorta and right atrium, respectively, to supply the heart muscle with oxygenated blood
Cardiac Neural Crest and Fetal Circulation
cells contribute to the development of the outflow tract and great vessels
relies on specialized shunts to bypass the non-functional lungs
Septation of the heart chambers and great vessels is crucial for establishing separate pulmonary and systemic circulations