Animation of the pathology of a thrombotic stroke, showing death of brain tissue due to a blocked cerebral artery. The point of view zooms in to a healthy brain, showing an artery (red) amongst millions of nerve cells (yellow). The artery opens to show normal blood flow. If the blood has a high level of low-density lipoprotein cholesterol (LDL, brown dots), white blood cells in the smooth muscle lining of the artery may ingest too much LDL, turning them into 'foam cells'. These may rupture and form a plaque of fat and dead cells, called atheroma. As the plaque grows it narrows the lumen of the artery, restricting blood flow. This can prompt the growth of a blood clot by the plaque, as platelets (grey) build up and trap blood cells, blocking the artery altogether. The zoom out shows cell death (black) due to a lack of oxygenated blood past the blockage, which in turn can cause the death of a substantial part of the brain. The symptoms of a stroke depend on the part of the brain affected, and can include partial paralysis, speed abnormalities and facial muscle weakness.