Fenestrations in the internal elastic lamina at bifurcations of human cerebral arteries

Abstract

Measurements of fenestratlons (or windows) in tbe Internal elastic lamina at the bifurcation of human cerebral arteries, were obtained from photomicrographs (scanning electron miscroscope). Thirteen of 28 bifurcations rerealed regions of enlarged fenestrations among tbe normal fenestions in tbe ridnity of the apex. Tbe mean diameter of the enlarged fenestradons (7.0 ± 0.34sem/an) was significantly greater dun die mean diameter (2.1 ± 0.13 sem μm) of die normal fenestrations. The number of fenestrations per sq mm was. less (2606 ± 284 sem per sq mm) for the enlarged fenestrations than for tbe normal fenestrations (4518 ± 397 sem persq mm). The proportion of tbe area of internal elastic lamina comprised of fenestrations Increased to 15.0 ± 1.1 sem percent for tbe enlarged fenestrations from a mean of 1.8 ± 0.16 sem percent for die normal fenestrations. Fenestrations from bifurcations without enlarged fenestrations, demonstrated characteristics similar to tbe normal fenestrations. More than 80% of tile specimens exhibited a gap in the internal elastic lamina in the apical region of die bifurcation. Based on a comparison of stress concentration factors, we propose that the presence of enlarged fenestrations represents a weakness in die internal elastic lamina at the bifurcation apex which may contribute to die initiation of mkroaneurysms. © 1981 American Heart Association, Inc.