Endothelial phagocytosis: An electron-microscopic study

Abstract

The RES of rats and mice was “overloaded” by repeated injections of colloidal carbon, and the non-RES vascular endothelium was examined by electron microscopy for evidence of phagocytosis. Phagocytosis of carbon was demonstrated in the endothelium of small myocardial vessels, in the endocardium, in pulmonary capillary endothelium, in the aorta, and in glomerular and peritubular capillary endothelium. Some carbon remained in the endothelium of the heart vessels for at least 7 days after overloading. Carbon particles were also present in circulating mononuclear cells and in perivascular phagocytes. This study thus confirms—at the level of the electron microscope—the ability of vascular endothelium outside the RES to perform phagocytosis.