Cerebral endothelial microvilli: formation following global forebrain ischemia.

Scanning electron microscopy (SEM) and morphometric procedures designed to survey large areas of intraparenchymal vasculature disclosed the widespread production of cerebral endothelial microvilli following global ischemia of the rat forebrain. Although these surface projections were present, they were infrequent, in sham-operated controls. As little as ten minutes of ischemia produced endothelial microvilli, which increased progressively in number with longer periods of ischemia. Transmission electron microscopy (TEM) performed on adjacent serial Vibratome sections confirmed these vascular alterations, although TEM sections did not permit an assessment of their numbers. Endothelial microvilli remained prominent in rats with up to four hours of postischemic recirculation. With SEM, these microvilli were sufficiently numerous so as to suggest that they may play a role in the development of the postischemic hypoperfusion documented by regional cerebral blood flow methods in this and other models of global cerebral ischemia.