Crohn's disease. Light micrograph (LM) of a section through an intestine in the early stages of Crohn's disease. Crohn's is a chronic inflammatory disorder of the intestines that causes ulceration and thickening of the lining. The cause of the disease is not clear, although it may be due to either an overactive or underactive immune system. There is no cure, although anti-inflammatory drugs and surgical removal of badly affected parts of the gut are often used. Magnification: x50 when printed at 10 centimetres tall. Human tissue.