EARLY HUMAN EMBRYO METABOLISM

Non-invasive microanalytical methods have been devised to study the en ergy metabolism of single human preimplantation embryos. Pyruvate, whi ch is added routinely to all media used to culture human embryos is co nsumed throughout the preimplantation period, with glucose assuming an increasing role at embryo compaction and blastocyst formation. All of the glucose consumed may be accounted for by the appearance of lactat e in the incubation medium. The enzyme hexokinase may be involved in r egulating this aerobic glycolysis. There is considerable indirect evid ence for the utilisation of endogenous as opposed to exogenous energy substrates, the most likely candidate being protein. Information on ea rly human embryo metabolism is likely to find application in a number of areas: these include the improvement of techniques for assisted hum an conception, notably in the selection of embryos for transfer follow ing In Vitro Fertilisation; the diagnosis of genetic defects at the pr eimplantation stage; increased understanding of the causes of implanta tion failure and miscarriage, and the development of novel post-coital contraceptives.