DIFFERENCES IN DEVELOPMENT OF CORONARY-ARTERIES AND VEINS

Objective: The differentiation of the coronary vasculature was studied to establish in particular the formation of the coronary venous syste m. Methods: Antibody markers were used to demonstrate endothelial, smo oth muscle, and fibroblastic cells in serial sections of embryonic qua il hearts. The anti-beta myosin heavy chain and the neuronal marker HN K-1 were added to our incubation protocol. Results: In HH32, the coron ary vascular network has developed into a circulatory system with conn ections to the sinus venosus, the aorta and the right atrium. The conn ections between the aorta and the right atrium allow for direct arteri ovenous shunting, Subsequently, differentiation into coronary arteries and veins occurs with an interposed capillary network. The smooth mus cle cells of the coronary arterial media derive from the subepicardial layer, whereas the subepicardially located cardiac veins recrute atri al myocardium, as these cells express the P-myosin heavy chain antigen . Ganglia are located in the subepicardium close to the vessels, while nerve fibres tend to colocalize with the formed vessel channels. Conc lusions: A new finding is presented in which the subepicardial coronar y veins have a media that consists of myocardial cells. The close posi tional relationship of neural tissue and coronary vessels that penetra te the heart wall is explained as inductive for vessel wall differenti ation, but not for invasion into the heart. (C) 1997 Elsevier Science B.V.