Uptake of pyruvate by early human embryos determined by a non-invasive technique.

Normal levels of pyruvate in freshly collected follicular fluid were found to be 0.45 mM, a value approximately 4 X that of serum. The utilization of pyruvate by human oocytes and early embryos has been measured, non-invasively, using two similar but separate analytical methods. The mature oocyte has a high level of pyruvate uptake (36 pmol/embryo/h). After fertilization this value falls, and then slowly increases to reach a peak just prior to the morula stage of 27 pmol/embryo/h before decreasing. Degenerating oocytes and embryos demonstrated much lower pyruvate uptake rates. The possible usefulness of this method for assessing embryo viability is discussed.