Creutzfeldt-Jakob disease. Light micrograph of a section through human brain showing Creutzfeldt- Jakob disease (CJD). A starchy brown plaque is seen amongst the black grains of the granular layer (at lower right). At upper centre a dark- pink brain cell (known as a purkinje cell) is also seen. This plaque and vacuole spaces are caused by a virus-like prion. As CJD progresses, brain tissue becomes spongy and nerve cells are destroyed. Symptoms include dementia and sudden muscle contractions, leading to death. There is concern that eating beef from mad cows" may cause CJD in humans. Magnification: x450 at 35mm size."