Written by Christian Nordqvist Copyright: Medical News Today Gangrene occurs when tissue dies (necrosis) because its blood supply is interrupted. Gangrene may be caused by an infection, injury, or a complication of a long-term condition that restricts blood circulation. It most commonly occurs in the extremities - the toes, fingers, arms and legs - but internal organs and muscles may also become gangrenous. There are five main types of gangrene : 1. Dry gangrene. 2. Wet gangrene. 3. Gas gangrene. 4. Internal gangrene. 5. Fournier's gangrene. What are the causes of gangrene ? Our cells require nutrients and oxygen to survive and they get this from our blood. If their blood supply goes down below a certain level, the cells will become damaged and will eventually die. Tissues and cells are also attacked by organisms such as bacteria, viruses, parasites and fungi. Our white blood cells and the Thymus cells (T-cells) form part of our immune system and fight germs. If the b