Morphological changes of microvessels in the brain with Alzheimer's disease

The pathological changes of microvessels in the cerebral cortex in Alzheimer's disease were examined at the ultrastructural level. With transmission electron microscopy (TEM), the endothelial cells of many capillaries and their pericytes exhibited atrophy and swelling with a narrowed lumen. The capillary basal laminas were thickened and tortuous. After isolation of the microvessels by ultrasonic treatment and collagenase digestion, the vascular wall structure was viewed by scanning electron microscopy (SEM). Most of the terminal arterioles had smooth muscle cells with an irregular shape and arrangement and often showed a series of focal constrictions. In some areas, the capillaries were arrayed in a bundle and terminated with tapered ends. Associated with the microvessels were fine filaments which may represent amyloid fibrils. The findings indicate that diffuse atrophy and the deletion of nerve cells in the cerebral cortex might be caused, at least partly, by a circulatory disturbance through the pathomorphologically changed microvessels.