Ultrastructural observations on the pathogenesis of aspirin-induced gastric erosions.

It is shown by transmission electron-microscopy that the first structural change in rats, following a dose of aspirin, is to the basement membrane of the endothelial cell of the capillary and post-capillary venule. This leads to the breakdown of small blood vessels before any other cytolytic effect. This is a focal effect and it is proposed that the erosion develops as an ischaemic infarct.