Development of the coronary blood supply: changing concepts and current ideas.

Earlier views of the development of the coronary vasculature included angiogenic budding and growth of arteries from the aortic sinuses and veins from the coronary sinus. The current concept begins with the establishment of the epicardium from the proepicardial organ, an outgrowth of the dorsal wall of the pericardial cavity. Capillaries form in a subepicardial mesenchymal population, extending as a plexus toward the truncus arteriosus and the atria.

Apoptosis during coronary artery orifice development in the chick embryo.

Previous studies regarding the development of proximal segments of the coronary arteries in the chick have demonstrated that these vessels do not develop as angiogenic outgrowths from the aorta. Rather, the proximal segments of the coronary arteries arise from a peritruncal capillary plexus in the epicardium that coalesces around the aortic and pulmonary outflow tracts. Vessels from the peritruncal plexus grow toward and attach to the aorta at about Hamburger and Hamilton (HH) Stage 32 to establish the definitive coronary circulation.

Apoptosis of endothelial cells in vessels affected by cerebral vasospasm.

Background: Cerebral vasospasm after subarachnoid hemorrhage is a prolonged contraction that leads to cerebral ischemia or infarction. Morphological studies of cerebral arteries during vasospasm have shown extensive necrosis of smooth-muscle cells and desquamation and dystrophy of endothelial cells. The mechanism of cellular death is unknown.