A STUDY OF COMPARATIVE HISTOLOGY AND MICROMETRY OF CORONARY ARTERIES OF DIFFERENT MAMMALS AND THE PATHOGENESIS OF ATHEROSCLEROSIS IN HUMAN

摘要

Coronary arteries are medium- sized muscular arteries or vasa vasorum supplying most of the wall thickness of myocardium; occlusion of these by atherosclerotic plaques leads to myocardial ischemia. In the present study a comparative histological observation was made on the coronary arteries of different mammals including human with special reference to atherosclerosis. Comparative histological observation and micrometry was done with H&E, Mason's Trichrome and Weigert's Van Gieson stained sections ofcoronary arteries. The tunica media and intima showed increased thickness in subjects where death was due to myocardial ischemia than in subjects where death was due to normal reasons; males & females were similarly affected by subintimal atherosclerotic plaques. The incidence of coronary artery disease was more in males than in females; the ratio observed in the above study was 3:2. Thickness of tunica media was more in males with narrower arterial lumen, as seen in the present study; henceforth contributing to poorer coronary perfusion in males than in females. The ratio of tunica intima and media was lower in cases of death due to myocardial infarction than in cases where death was due to normal reasons, indicating intimal thickening of coronary arteries in ischemic heart disease. Measurements of tunica media remained unchanged in all subjects, suggesting less involvement of tunica media in atherosclerosis. Comparative histology of mammalian coronary arteries showed thicker sub-endothelial connective tissue with intimal collagen & elastic fibres and more smooth muscle layers in tunica media in human than in sheep and goat. The present study also shows thicker arterial wall (on micrometry) with prominent internal elastic lamina in sheep, with marked resemblance to human coronary arteries, thus making it an ideal experimental animal model for coronary artery bypass graft surgery.