glycogen

n. starch-like substance present in animal tissues which may be converted into dextrose

Glycogen is a polysaccharide of glucose (Glc) which functions as the primary short term energy storage in animal cells. It is made primarily by the liver and the muscles, but can also be made by the brain, uterus, and the vagina. Glycogen is the analogue of starch, a less branched glucose polymer in plants, and is commonly referred to as animal starch, having a similar structure to amylopectin. 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). In the liver hepatocytes, glycogen can compose up to 8% of the fresh weight (100–120 g in an adult) soon after a meal. Only the glycogen stored in the liver can be made accessible to other organs. 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. The uterus also stores glycogen during pregnancy to nourish the embryo.
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(n.)
A white, amorphous, tasteless substance resembling starch, soluble in water to an opalescent fluid. It is found abundantly in the liver of most animals, and in small quantity in other organs and tissues, particularly in the embryo. It is quickly changed into sugar when boiled with dilute sulphuric or hydrochloric acid, and also by the action of amylolytic ferments.
  

A starchlike glucose polymer that is the main form in which carbohydrates are stored in humans and other animals and is the chief source of stored fuel in humans.

the form of glucose found in the liver and muscles.