Gangrene refers to the special morphological changes caused by the infection of secondary spoilage bacteria after tissue necrosis. The necrotic tissue is decomposed by spoilage bacteria to produce hydrogen sulfide, which combines with the iron decomposed by hemoglobin to form iron sulfide, making the necrotic tissue black. Gangrene can be divided into dry gangrene, wet gangrene and gas gangrene. Dry gangrene is more common in the limbs of atherosclerosis, frostbite and other diseases. The lesion is dry and shriveled, dark brown, and has obvious boundaries with other normal tissues around it. Wet gangrene often occurs in internal organs communicating with the outside world, such as intestines, lungs and uterus. Spoilage bacteria are seriously infected. Local swelling is obvious, dark green or dark black. It will cause the whole body to be halfway. Gas gangrene is a special type of wet gangrene, which is mainly seen in severe open wounds touching muscles and complicated with anaerobic bacteria infection such as Clostridium perfringens. When bacteria divide necrotic tissue, they will produce a lot of gas, which will make the tissue feel distorted. It is developing rapidly and needs timely treatment. I hope it helps you.