Influence of epidermal growth factor and transforming growth factor-α on <i>in vitro</i> maturation of cumulus cell-enclosed bovine oocytes in a defined medium

This study was carried out to determine the effects of growth factors (epidermal growth factor, transforming growth factors-alpha and -beta 1, basic fibroblast growth factor, insulin), gonadotrophins (LH, FSH), and fetal bovine serum added to TCM199 medium on cumulus expansion and fertilization during in vitro maturation, and on subsequent embryonic development of bovine cumulus cell-enclosed oocytes. Epidermal growth factor, transforming growth factor-alpha, LH and FSH enhanced cumulus expansion and oocyte fertilizability. No significant effect was achieved with transforming growth factor-beta 1 nor with basic fibroblast growth factor. No additive stimulation on cumulus expansion and oocyte fertilizability was observed when epidermal growth factor was combined with LH or FSH. The addition of either epidermal growth factor or transforming growth factor-alpha to the maturation medium increased the number of fertilized ova that developed to the blastocyst stage. These results demonstrate the potential use of epidermal growth factor and transforming growth factor-alpha in obtaining high quality mature bovine oocytes for in vitro fertilization.