Thrombosis induced in vivo in the mesenteric artery of normal and thrombocytopenic rats, an electron-microscopic study of the early arterial wall reaction.

Arteries taken from 1 to 3 days after local thrombosis had been induced by the passage of a weak electric current followed by the topical administration of ADP were studied by electronmicroscopy. The characteristic changes observed during this period included total disappearance of pre-existing thrombi, rapid reconstitution of the endothelium and important hypertrophy of smooth muscle cells in the media. Thrombocytopenia induced by the administration of antiplatelet serum produced no alterations in untreated arteries. When it was coupled to thrombus induction, healing of injured endothelial and smooth muscle cells was grossly impaired, hypertrophy of the media was absent and fibrin infiltrated the arterial wall at the site of thrombus induction. These results bring support to the view that blood platelets play an important role in the induction of the regeneration response of injured arterial cells.