ABSTRACT
The placenta is a specialized organ that exchanges nutrients, gases, and waste products between the umbilical circulation of the fetus and the uterine circulation of the pregnant mother. In addition to the exchange or transfer of materials, the placenta is a highly metabolically active organ; for example, it consumes oxygen and glucose at very high rates, approaching those of brain and tumor tissue. Many other metabolic activities have been documented from a variety of in vivo and in vitro studies, including glycolysis; gluconeogenesis; glycogenesis; oxidation of glucose, lipids, and amino acids; amino acid deamination and interconversion; ammonia production; protein synthesis; triglyceride synthesis; and modification of fatty acid chain length. This impressive array of metabolic activities represents not only the metabolic requirements of an active organ of exchange but also provides the means by which the placenta can regulate the quantity as well as the type of nutrients transferred to the fetus. It is critical to a complete understanding of the supply of nutrients to the fetus for fetal growth and development, and necessary, therefore, to consider in detail the metabolism of the placenta.
