Hematogenic cell infiltration of the aortic intima in normal and hypercholesterolemic swine

The incidence of periendothelial (epi-, inter- and subendothelial) round cells in en face endotheliumintima preparations and cross-sections of swine aortas was determined. The round cell count of Sudanpositive and -negative intimai areas of thoracic and abdominal aortas of animals fed an atherogenic diet was compared with Sudan-negative areas of animals on normal food. Furthermore, spontaneous lesions at the aortic trifurcation in swine and abdominal aortic segments of humans with different stages of arteriosclerosis were studied and the aorta endothelium of normal animals was examined with a scanning electron microscope. According to these studies, round cells (monocytes or lymphocytes occur in the subendothelium as a normal constituent of the aortic intima. They are increased in spontaneous lesions and more frequent in induced fatty streaks. In swine, they participate primarily in intracellular lipid storage in Sudan-positive intimal areas. Their function in normal intima and in low-lipid intimal thickening is unknown. Similar observations were made with regard to the human abdominal aorta.