Differential pH in embryo culture.

To determine the optimum pH in sequential media for embryo culture around the fertilization-zygote stage and cleavage stage, with use of a mouse embryo assay. Experimental laboratory study. University Hospital and University Research Unit. F1 hybrids between CD1 female and BDF male mice. Fertilized, one-cell mouse embryos were cultured 5 days in test media where pH was changed at defined time intervals. Percentage of good-quality embryos, defined by strict morphology. A significantly improved development was observed when pH was as high as 7.30 before the pronuclear stage and lowered to pH 7.15 during the cleavage period. Good embryo development is consistent with two different pH values in sequential culture media. This could have important implications for embryo culture in human IVF.