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Glycogen (commonly known as animal starch although this name is inaccurate) is a polysaccharide that is the principal storage form of glucose (Glc) in animal cells. Glycogen is found in the form of granules in the cytosol in many cell types, and plays an important role in the glucose cycle. Glycogen forms an energy reserve that can be quickly mobilized to meet a sudden need for glucose, but one that is less compact than the energy reserves of triglycerides (fat). Only the glycogen stored in the liver can be made accessible to other organs, and these hepatocytes have the highest concentration of it—up to 8% of the fresh weight in well fed state, or 100–120 g in an adult. In the muscles, glycogen is found in a much lower concentration (1% of the muscle mass), but the total amount exceeds that in liver. Small amounts of glycogen are found in the kidneys, and even smaller amounts in certain glial cells in the brain and white blood cells.