Electron Microscopic Observations on Human Intracranial Arteries: Channges Seen With Aging and Atherosclerosis

There are many questions concerning aging and atherosclerosis and their interrelationship which remain to be answered. There have been no systematic studies on the ultrastructural alterations of intracranial arteries throughout the human life span although observations have been made on human aortas and coronary arteries^1-3 and plaques in intracranial vessels.⁴ Electron microscopic observations of "normal" intracranial vessels from individuals who died in the first decade have been previously reported from our laboratories.⁵ While there are a number of electron microscopic studies on experimentally produced systemic vascu' lar diseases in animals^6-13 as well as on changes in systemic vessels in aged swine,¹⁴ a study of human vessels seems the most appropriate way to investigate the relation of ultrastructural changes to the prolonged human life span, that is, to "aging." It is recognized that although certain fine structural details and relationships are less clearly defined in human