ROLE OF EPIDERMAL GROWTH-FACTOR AND INSULIN-LIKE GROWTH-FACTOR-I ON PORCINE OOCYTE MATURATION AND EMBRYONIC-DEVELOPMENT IN-VITRO

The effects of epidermal growth factor (EGF) and insulin-like growth f actor-I (IGF-I) on the in vitro maturation of porcine oocytes were exa mined. Oocytes obtained from the ovaries of slaughtered prepubertal gi lts were matured in modified Medium 199 supplemented with 25% porcine follicular fluid and gonadotropins, and fertilized in vitro. Oocytes w ere either fixed 16 h later to assess fertilization or cultured for 7 days to assess embryonic development. In Experiment 1, the addition of EGF to maturation medium increased the percentage of meiotically matu re oocytes (88% v. 70%; P < 0.001) but did not affect the proportion o f fertilized or cleaved oocytes. Blastocysts derived from oocytes matu red in medium supplemented with 10 ng mL(-1) EGF had a greater number of cells compared with those of control blastocysts (51.1+/-5.1 v. 36. 0+/-3.1; P < 0.02). In Experiment 2, the addition of IGF-I to maturati on medium had no effect on meiotic maturation, fertilization or embryo nic development. Our findings demonstrate that EGF plays an important role in both the meiotic and cytoplasmic maturation of porcine oocytes in vitro.