RELATIONSHIPS BETWEEN ENERGY-METABOLISM AND DEVELOPMENT OF EARLY MAMMALIAN EMBRYOS

Early embryo development requires the production and expenditure of large amounts of cellular energy for cell growth, division and differentiation. Consequently, information about energy metabolism is important for both fundamental and applied aspects of embryo biology. During early cleavage, the in-vitro development of embryos from a number of mammalian species is inhibited by glucose, hypoxanthine, and oxygen, and favoured by glutamine and antioxidants. The common factor in these effects may be oxygen radicals, which are severely detrimental to early embryo development. Glucose, hypoxanthine and oxygen can all increase the cellular production of oxygen radicals, while antioxidants can detoxify them. Glutamine metabolism can provide reducing equivalents for energy production and to counteract lipid peroxidation, under conditions where the metabolism of other substrates cannot. An understanding of the mechanisms of production and elimination of oxygen radicals in embryos may lead to significant improvements in the success of embryo culture and the practical techniques which depend on it.