Lines of Zahn

Lines of Zahn are a characteristic of thrombi that appear particularly when formed in the heart or aorta. They have visible and microscopic alternating layers (laminations) of platelets mixed with fibrin, which appear lighter, and darker layers of red blood cells. Their presence implies thrombosis at a site of rapid blood flow that happened before death. In veins or smaller arteries, where flow is not as constant, they are less apparent.