This study was conducted to examine the effect of epidermal growth factor (EGF) and 17β-estradiol (E2) on nuclear and cytoplasmic (male pronuclear formation and early embryo development) maturation of porcine oocytes. Oocytes were aspirated from antral follicles and cultured in modified TCM-199 medium supplemented with 0.57 mM cysteine, 10 IU/ml eCG, 10 IU/ml hCG, with or without EGF and/or E2. In vitro fertilisation of matured oocytes was performed in a modified Tris-buffered medium (mTBM) with frozen-thawed ejaculated spermatozoa. Oocytes were transferred to NCSU-23 supplemented with 0.4% bovine serum albumin at 6 h after in vitro fertilisation. Significantly higher (p < 0.05) rates of nuclear maturation, pronuclear formation and cleavage (91.7%, 65.2% and 37.3%, respectively) were observed when oocytes were cultured in the medium containing both EGF (10 ng/ml) and E2 (1 μg/ml) than in the medium supplemented with either EGF or E2 or without both. Intracellular glutathione concentration in the oocytes cultured in the medium containing both E2 and EGF was also significantly higher (12.1 pmol per oocyte) than that of oocytes cultured in the medium with E2 or EGF alone or without both. These findings suggested that EGF and E2 have a synergestic effect on both nuclear and cytoplasmic maturation of porcine oocytes.
Enhancement of cumulus expansion and nuclear maturation during bovine oocyte maturation in vitro by the addition of epidermal growth factor and insulin-like growth factor I
