A comparison between aortic lumen surfaces of hypertensive and hypotensive turkeys.

Some features of the aortic intima were examined with the scanning electron microscope (SEM) and found to contribute to the etiology of dissecting aneurysm. The endothelium over intimal plaques was not as pendulous as endothelium surrounding plaques. The pendulous appearance of aortic endothelial cells could be associated with the contractile nature of these cells. Some undescribable factor, which has been termed stress or atherosclerosis, seemed to reduce the contractile nature of endothelial cells on the plaque areas. Analyses with SEM revealed a probable cause of a dissecting aneurysm. The effect of pulsating blood pressure on an inelastic endothelium could create a separation between endothelial cells and the fluid pressure of blood could then separate the tissue until the vessel ruptured into the body cavity or back into the aorta. Because all abdominal aortic segments examined had atherosclerosis, it was not possible to show the amount of intimal alteration between normal and atherosclerotic aortas. Each blood pressure line showed a similar change which was 4.52 and 4.95% for the high and low blood pressure lines, respectively. There were no demonstrable correlations in this study between either high or low blood pressure lines of turkeys and atherosclerosis.