THE DEVELOPMENT OF THE CORONARY VESSELS AND THEIR DIFFERENTIATION INTO ARTERIES AND VEINS IN THE EMBRYONIC QUAIL HEART

Research concerning the embryologic development of the coronary plexus has enriched our understanding of anomalous coronary vessel patternin g. However, the differentiation of the coronary vessel plexus into art eries, veins, and a capillary network is still incomplete. Immunohisto chemical techniques have been used for whole mounts and serial section s of quail embryo hearts to demonstrate endothelium, vascular smooth m uscle cells, and fibroblasts. From HH35 onward, the lumen of the coron ary plexus was visualized by injecting India ink into the aorta. In HH 17, branches from the sinus venosus plexus expand into the proepicardi al organ to reach the dorsal side of the atrioventricular sulcus. From HH25 onward, vessel formation proceeds toward the ventral side and th e apex of the heart. After lumenized connections of the coronary vesse ls with the aorta and right atrium are established, a media composed o f smooth muscle cells and an adventitia composed of procollagen-produc ing fibroblasts are formed around the coronary arteries. In the early stage, bloodflow through the coronary plexus is possible, although con nections with the aorta have yet to be established. After the coronary plexus and the aorta and right atrium are interconnected, coronary ve ssel differentiation proceeds by media and adventitia formation around the proximal coronary arteries. At the same time, the remodeling of t he vascular plexus is manifested by disappearance of arteriovenous ana stomoses, leaving only capillaries to connect the arterial and venous system. (C) 1997 Wiley-Liss, Inc.