En face morphology of endothelial junctions

Abstract

Silver-stained preparations of vascular endothelium exhibit small structures called stomas whose origin is unclear. In this study non-silver-stained preparations of rat aorta were examined by scanning electron microscopy and stoma-like structures were formed by extensive membrane overlap of one cell over another at the cell junction. In some circumstances the degree of overlap was so extensive that large flaps appeared almost isolated from the cytoplasm of the main cell body. These structures were identical in size and their location to stomas seen in silver-stained preparations. Stomas may therefore be simply large membrane flaps.