ASCORBATE-SUPPLEMENTED MEDIA IN SHORT-TERM CULTURES OF HUMAN EMBRYOS

The present study aimed to evaluate whether ascorbate, a reactive oxyg en 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, wh ich contains iron and copper in its formulation. Human oocytes, sperma tozoa and embryos from 83 infertile IVF couples were randomly allocate d and cultured in the presence or absence of 62.5 mu M ascorbate in HT F medium (39 couples) or Ham's F-10 medium (44 couples). No significan t effect of ascorbate on fertilization, number of cells and embryo gra de per embryo on days 2 and 3 after insemination, or percentage of emb ryos showing developmental block on day 3 (those embryos that were sti ll 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 eithe r 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 concen trations of ascorbate and longer-term embryo cultures (to the blastocy st stage) have been tested.