THE DEVELOPMENT OF PREATHEROSCLEROTIC CORONARY-ARTERY LESIONS IN PERINATAL PIGLETS

The fine structure and ultrastructure of the anterior descending coron ary artery were studied in a series of perinatal piglets at 1 week pri or to birth, and at 8, 24, 72 and 168 h after birth. In the anterior d escending coronary artery, at or just distal to the branch point of th e left circumflex artery, early plaque-like intimal lesions were prese nt in the majority of animals, These consisted of subendothelial edema , fragmentation and dissolution of the internal elastic lamella, and t he appearance of intimal myoid cells known as modified smooth muscle c ells (MSMCs), These changes were present in all piglets at and before 8 h of age, They persisted and progressed during the first week of lif e in about half of the piglets, Beginning at 72 h and continuing throu gh 168 h, there was an increase in MSMCs and the appearance of fibrobl asts, Both fibroblasts and MSMCs were associated with the elaboration of dense collagen fibrils, Foamy macrophages appeared within the suben dothelial intima having the appearance of lipophages, While the preval ence of these changes at birth indicates that they may be part of norm al development, their persistence in half the piglets and structural f eatures suggest reaction to intimal injury beginning prenatally. The l esions may be precursive of coronary atherosclerosis later in life and may parallel the early stages of atherogenesis in humans. (C) 1996 S. Karger AG, Basel