Embryology of the Heart Development

Study Notes

Development of the heart involves forming a heart tube and a pericardial cavity.
The heart tube initially develops in the cranial aspect of the embryo and then moves down into the thorax.
Mesoderm differentiates into angioblasts and hemocytoblasts under the influence of vascular endothelial growth factor (VEGF).
VEGF stimulates lateral plate mesoderm to form heart tubes and pericardial cavities.
During lateral folding, heart tubes and pericardial cavities fuse to form one heart tube and one pericardial cavity.
Dorsal mesocardium connects the pericardial cavity to the heart tube.
The heart tube consists of endocardium (inner layer) and myocardium (outer layer with cardiac myocytes).
Cardiac jelly, secreted by myocardium, sits between the endocardium and myocardium.
Cranio-caudal folding moves the heart tube from above the head into the thorax.
Different parts of the heart tube (truncus arteriosus, bulbous cordis, primitive ventricle, primitive atria, sinus venosus) develop into specific structures in the adult heart.
Truncus arteriosus becomes pulmonary trunk and aorta, bulbous cordis becomes the right ventricle, primitive ventricle becomes the left ventricle, and primitive atria become the left and right atrium.- The structure below the primitive atria is called the sinus venosus, which receives inflow from three tracts entering into the sinus venosus via horns named left and right horns.
Veins entering the sinus venosus include the common cardinal veins, umbilical veins, and vitelline veins.
Cardiac looping is crucial for heart development and depends on proteins called dyneins; abnormalities in this process can lead to conditions like dextrocardia or situs inversus.
During cardiac looping, the truncus arteriosus and bulbous cordis move downward and to the right initially.
The visceral pericardium is formed by cells moving from the sinus venosus into the pericardial cavity during development.
Neural crest cells migrate and form endocardial cushions, which fuse to create the septum intermedium, separating the primitive atria from the primitive ventricle.
The septum intermedium gives rise to the right and left AV canals, with valve formation leading to the mitral valve on the left and tricuspid valve on the right.
The septum primum grows downward towards the septum intermedium, creating a space called the ostium primum; later, it closes off and forms the ostium secundum.
The foramen ovale, a structure between the septum secundum and ostium secundum, allows blood to bypass the lungs in utero; if it remains open, it can lead to a patent foramen ovale and potential complications like paradoxical embolus.- The heart development process involves the formation of various structures including the left atrium, right atrium, left ventricle, right ventricle, right AV canal, and left AV canal.
The development of the interventricular septum includes the formation of the muscular portion and the membranous portion to prevent ventricular septal defects.
Inflow tracks into the right atrium are established through the fusion of the left and right horns into the sinus venosus, leading to the formation of the coronary sinus and superior/inferior vena cava.
The bulbous cordis and truncus arteriosus contribute to forming the aortico-pulmonary septum, separating the aorta and pulmonary trunk.
Blood flow from the left ventricle passes through the aortic arch, while blood from the right ventricle flows through the pulmonary trunk.
The aortico-pulmonary septum causes a rotation of the aortic and pulmonary trunks, leading to a distinct separation of blood flow between the aorta and pulmonary trunk.
The development of semilunar valves involves the formation of endocardial cushions at the junction of the bulbous cordis and conus cordis, leading to the differentiation of valves for the aorta and pulmonary trunk.

Description

Learn about the intricate process of heart development in embryos, including the formation of heart tubes, pericardial cavities, and various heart structures. Explore how angioblasts, hemocytoblasts, VEGF, cardiac looping, and neural crest cells play crucial roles in shaping the heart. Understand the significance of structures like the sinus venosus, septum intermedium, AV canals, foramen ovale, and interventricular septum.