title: Nutritional and metabolic requirements of early cleavage stage embryos and blastocysts.
abstract: During preimplantation human embryo development there is an increase in the synthesis of macromolecules and a demand for energy. Consequently, the metabolic requirements of the human embryo change as development proceeds from the zygote to the blastocyst stage. Evidence from a number of species indicates that before activation of the embryonic genome, human and other mammalian embryos have a preference for oxidizable energy substrates, particularly pyruvate, non-essential amino acids and glutamine. After embryonic genome activation, glucose and essential amino acids become increasingly important. As such, there is a switch in energy metabolism during preimplantation development from one based principally on aerobic respiration, to another based on oxidative metabolism and aerobic glycolysis.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Sheffield, Jessop Hospital for Women, Sheffield S3 7RE, UK.
authors.forename: Karen L.
authors.initials: KL
authors.lastname: Martin