Coronary Vasculature
The coronary vasculature contains the arteries and veins of the heart muscle (myocardium). Prior to looping, the primary heart tube consists of endocardium, cardiac jelly, and myocardium. Epicardial cells derived from the splanchnopleuric mesoderm migrate between days 22 and 28 of human development from the proepicardial organ to form an outer layer of the primary heart tube when the tube initiates looping. The proepicardial organ is a clustering of cells in the dorsal mesocardium of the sinus venosus or septum transversum. The added layer called epicardium will turn into the coronary vasculature.
The coronary vasculature is structured in three linages of cells: smooth muscle, endothelial, and connective tissue. Those cells are segregated prior to migration in the proepicardial organ. After movement, cells result in a continuous simple squamous epithelium that covers the heart and the body wall. Via the process of vasculogenesis, the cells fuse to form the coronary vessels de novo.
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