Atherosclerosis. Coloured light micrograph of a cross-section through an artery obstructed with atheroma plaque. This arterial disease is known as atherosclerosis. The muscular wall of the artery (orange) takes up much of the image. At centre, fatty deposits of plaque (grey) are seen on the inner arterial wall; the lumen (black) has been severely reduced for the flow of blood. Athero- sclerosis, the thickening on inner artery walls, is mainly due to a fatty diet high in cholesterol. Narrowing of the artery, as here, disrupts blood flow and may result in clot formation or severe artery blockage which can prompt a heart attack. Magnification: x50 at 6x4.5cm size.