Abstract：There is not synchronized between nuclear maturation and cytoplasmic maturation of in vitro maturated oocytes. In order to solve this problem, we use butyrolactone I (BL-Ⅰ), cdc2 kinase inhibitor, to prevent porcine oocyte nuclear maturation in vitro. Porcine oocytes were cultured for 44 h in the medium containing different concentrations of BL-Ⅰ(0, 10, 20, 40 and 80 mol/L, respectively). With the increase of BL-Ⅰ concentration, the inhibition efficiency on maturation of porcine oocytes was increased. When treated with BL-Ⅰ in 20, 40 and 80 mol/L, respectively, the oocytes reached 25%, 47% and 67%, respectively, at germinal vesicle(GV) stage, and 38%, 9% and 0% at MII stage, which were both significant difference with control group. In addition, After removed BL-Ⅰand incubated for additional 44 h in ooycte maturation media, these oocytes at MⅡ stage were significant increased and reached 51%, 47% and 5%, respective, which showed the BL-Ⅰinhibition to maturation of oocytes is reversible. Additionally, oocytes incubated with 20 μmol/L BL-Ⅰ for 20 and 24 h without BL-Ⅰ (20 h＋+24 h-treatment group), showed low percentage at MⅡ stage compared with the control group (culture for 44 h without BL-Ⅰ) (P < 0.05, 65.6% vs 70.1%). When the matured oocytes from 20 h＋+24 h- treatment group were parthenogenetic activated, the cleavage rate, blastocyst rate and blastocyst total cell number had increased, but no significant difference compared with the control group. When the matured oocytes were used for nuclear transfer, the cleavage rate, blastocyst rate and blastocyst total cell number were better than that of the control group, but only significant difference in cleavage rate (P <0.05, 69% vs 62%). These results indicate that BL-Ⅰ can significantly inhibit the porcine oocytes maturation, and that the inhibition can be reversed by removing BL-Ⅰ. These results also show that matured oocytes treated with the proper concentration of BL-Ⅰ can slightly improved the development ability of parthenogenetic and nuclear transfer embryos.
