The primary reserve polysaccharide of the animal world. It is found in the muscles and livers of all higher animals, as well as in the cells of lower animals. Because of its close relationship to starch, it is often called animal starch, although glycogen is found in some lower plants, fungi, yeast, and bacteria. A polysaccharide similar to glycogen was isolated in one case from a higher plant, Golden Bantam sweet corn (Zea mays).