Fertilization and early embryology: Ascorbate-supplemented media in short-term cultures of human embryos

The present study aimed to evaluate whether ascorbate, a reactiveoxygen species (ROS) scavenger, can improve fertilization anddevelopment of human embryos in vitro when added to the simplesalt solution human tubal fluid (HTF) or the complex tissueculture medium Ham's F-10, which contains iron and copper inits formulation. Human oocytes, spermatozoa and embryos from83 infertile IVF couples were randomly allocated and culturedin the presence or absence of 62.5 _µM ascorbate in HTFmedium (39 couples) or Ham’s F-10 medium (44 couples).No significant effect of ascorbate on fertilization, numberof cells and embryo grade per embryo on days 2 and 3 after insemination,or percentage of embryos showing developmental block on day3 (those embryos that were still at the 2-cell stage) was observedwhen data were analysed together or divided into several groupsaccording to the cause of infertility, quality of semen sampleused for insemination and women‘s age in either of thetwo media tested. Despite these results, a positive effect ofascorbate on fertilization and embryo development in vitro cannotbe totally ruled out until the effects of other, non-physiologicalconcentrations of ascorbate and longer-term embryo cultures(to the blastocyst stage) have been tested.