EFFECT OF A SERUM EXTENDER CONTAINING GROWTH-FACTORS ON DEVELOPMENT OF IVM AND IVF BOVINE EMBRYOS

The present experiments were conducted to determine if supplementation of the culture medium with a serum extender containing growth factors would increase development of bovine embryos into morulae or blastocy sts, following in vitro maturation (IVM) and in vitro fertilization (I VF). In Experiment 1, bovine zygotes were cultured in CR1 medium suppl emented with 0, 0.01, 0.1, 1 or 10% serum extender. In Experiment 2, b ovine zygotes were cultured in the presence of cumulus cells in CR1 me dium supplemented with 0, 0.01, 0.1, 1 or 10% serum extender. In Exper iment 3, bovine oocytes were matured in Medium 199 supplemented with 0 , 0.01, 0.1, 1 or 10% serum extender. In Experiment 4, oocytes were ma tured in Medium 199 with 10% fetal bovine serum (FBS) or 5% FBS with s erum extender. Following maturation, zygotes were cultured in CR1 medi um with 10% FBS or 5% FBS and serum extender. In all 4 experiments, th e embryos were cultured in vitro until Day 7 after IVF, and developmen t to the morula or blastocyst stage was assessed. The findings of the first 2 experiments showed that the serum extender did not directly in fluence embryo development but did stimulate development when cumulus cells were included in the culture system. The remaining 2 experiments showed that the serum extender did influence development through its interactions with cumulus cells during maturation and/or culture. Thes e findings suggest that although growth factors or other products do n ot directly stimulate bovine embryo development their effects may be m ediated through secondary cell systems.