Let’s go back to the 4th week during the development of heart. The primitive intraembryonic coelom forms in the lateral and cardiogenic mesoderm during 4th week of development. Like the heart fields, the intraembryonic coelom has a horse-shoe configuration during this period: A thick mesodermal plate called “septum transversum” lies … Continue reading Diaphragm and Body Cavities Development – Embryology Made Easy