Light micrograph of a section through a human coronary artery: the lumen (interior) is entirely blocked by the development of a thrombus (clot) on the surface of an atheromatous plaque. The plaque appears white at bottom right with the thrombus (pink) immediately to its left. Atheroma and thrombus largely obstruct the entire lumen. The remaining lumen is occupied by bright red postmortem blood coagulum - tightly packed red blood cells. Here, the obstruction in the coronary artery resulted in a sudden cessation of blood supply to a section of the heart muscle, an event known as an acute myocardial infarction - a fatal heart attack. UFig. 7.6 Basic Histopathology U