Distribution and Endothelial Morphology of Atherosclerotic Lesions at Bifurcations and Curves of Human Cerebral Arteries

Abstract

The present study was an attempt to clarify mechanisms related to the development of atherosclerotic lesions at branches and curves in the human arterial tree. The distribution of atherosclerotic lesions, including cloudy thickenings, fatty streaks, fibrous plaques and complicated lesions, was investigated at bifurcations and curves of cerebral branches of the internal carotid artery. Morphological changes of the endothelium over fibrous plaques at bifurcations was also assessed, by means of scanning electron microscopy. Early atherosclerotic lesions occurred predominantly at the outer walls of bifurcations and distal to the center of the inner curvature at curves, where wall shear stress is considered to be low. In contrast, the flow divider of bifurcations and the outer curvature of the bends, presumably high-shear regions, were free of early lesions. Endothelial cells over fibrous plaques without sudanophilia(FP) and with sudanophilia(SP) were significantly less elongated than those in lesion-free areas. In addition, endothelial cells over the FP and SP showed significantly more microvillous projections than did those in lesion-free areas. These results suggest that focal hemodynamic forces are implicated in the development of the atherosclerotic lesions.