Cholesterol crystals in an atherosclerotic plaque.

This picture shows the depths of a plaque. The cholesterol crystals appear to be needle-shaped. They are actually rectangles in cross-section. The surrounding tissue is all necrotic (dead) debris. When this material ruptures from the plaque into the bloodstream, it makes the blood clot. This causes myocardial infarcts, strokes, gangrene, etc.