Carl Ferdinand Cori (1896-1984) was awarded a quarter of the 1947 Nobel Prize in Physiology or Medicine for his discovery of how glycogen is broken down and resynthesized in the body to be either stored or used as a source of energy. After immigrating to America in 1922, Cori, along with his wife Gerty, studied the fate of sugar in animals and the effects of insulin and epinephrine. His work on carbohydrate metabolism was first performed on animals, then on isolated tissues. He later studied tissue extracts and isolated enzymes, some in crystalline form. In 1936, he isolated glucose-1-phosphate â€“ also called the Cori ester -- as the direct product of a reaction in which glycogen phosphorylase cleaves off a molecule of glucose from glycogen. This discovery made possible the enzymatic synthesis of glycogen and starch in vitro. Subsequently, phosphorylase and other enzymes were crystallized. Cori also carried out several studies on the pituitary gland. He observed that the marked decrease in glycogen and lowering of blood sugar in rats to which the pituitary gland was surgically removed were correlated with an increase in the rate of glucose oxidation.