Study of esterase-positive cells in swine atherosclerosis

Non-specific esterase activity was studied by light and electron microscopic histochemistry after 6 mos of progression of injury and diet-induced atherosclerotic lesions in the swine aorta, and after 6 wks, 5 mos and 14 mos on regression regimen. At each time period three cellular patterns of reaction product (RP) were seen, round cells with dense RP, elongate cells with dense "granules" of RP, and large "foamy" cells with very faint RP. Ultrastructurally, RP was found in macrophages, smooth muscle cells and foam cells. The number of esterase-positive cells decreased with time and the disappearance of necrosis.