Light micrograph of a section through a human coronary artery, showing the partial obstruction of the interior (lumen) due to the formation of a large atheroma plaque (pink, at top). The consequent reduction in blood flow leads to ischaemia of the heart muscle (myocardium) that the vessel supplies. Partial obstruction by atheroma formation is common in the coronary arteries of male cigarette smokers, where it provokes the symptoms of Iangina pectoris i, a gripping pain in the chest that is experienced on exertion & disappears with rest. UFig. 7.4 BASIC HISTOPATHOLOGY