Ascorbate-supplemented media in short-term cultures of human embryos

The present study aimed to evaluate whether ascorbate, a reactive oxygen species (ROS) scavenger, can improve fertilization and development of human embryos in vitro when added to the simple salt solution human tubal fluid (HTF) or the complex tissue culture medium Ham's F-10, which contains iron and copper in its formulation. Human oocytes, spermatozoa and embryos from 83 infertile IVF couples were randomly allocated and cultured in the presence or absence of 62.5 microM ascorbate in HTF medium (39 couples) or Ham's F-10 medium (44 couples). No significant effect of ascorbate on fertilization, number of cells and embryo grade per embryo on days 2 and 3 after insemination, or percentage of embryos showing developmental block on day 3 (those embryos that were still at the 2-cell stage) was observed when data were analysed together or divided into several groups according to the cause of infertility, quality of semen sample used for insemination and women's age in either of the two media tested. Despite these results, a positive effect of ascorbate on fertilization and embryo development in vitro cannot be totally ruled out until the effects of other, non-physiological concentrations of ascorbate and longer-term embryo cultures (to the blastocyst stage) have been tested.