Embryology of the Heart II

Summary of the video for your notes: 1. The heart is developed from the splanchnic (lateral plate) mesoderm. 2. Atrioventricular endocardial cushions at anterior and posterior walls appear and proliferate until they fuse, turning a single lumen into two. The two canals are the right and left atrioventricular orifices. 3. Once fused, the AV orifices are surrounded by proliferations of mesenchymal tissue. 4. The bloodstream hollows out and thins tissue on the ventricular surface of these proliferations forming the valves and the muscular cords. 5. Muscular tissue in the cords degenerate and is replaced by dense connective tissue. 6. The valves are now connected to thick trabeculae (papillary muscles) by the chordae tendinae. 7. Development of the conotruncal ridges and closure of the interventricular foramen occur by proliferations of the right and left conus cushions, as well as the proliferation of the anterior endocardial cushion - this closes the interventricular foramen and form the membranous portion of the interventricular septum.