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The aim of the present study was to examine the rate of activation and time-dependent changes in p34 cdc2 kinase and MAP kinase activities in porcine oocytes after injection of sperm extracts (SE) or treatment with Ca 2+ ionophore to clarify whether SE injection is useful for porcine oocyte activation. SE was prepared from miniature pig sperm by non-ionic surfactant. Oocytes that were treated with Ca 2 + ionophore and injected with SE were activated at rates of 41% and 46%, respectively. The activities of p34 cdc2 kinase and MAP kinase in each culture period (4, 8 and 12 h) in the Ca 2+ ionophore group and SE injection group were significantly lower than those in the control group. These results suggest that SE injection induces decrease of p34 cdc2 kinase and MAP kinase activity, and induces oocyte activation, as well as Ca 2+ ionophore treatment, but the induction was comparatively limited.

This study examined embryo development of porcine oocytes after microinjection of sperm extracts (SE) in porcine intracytoplasmic sperm injection (ICSI). SE was prepared from miniature pig sperm by a nonionic surfactant, and various concentrations (0.02, 0.04 and 0.08 mg/mL) of SE were injected into the matured oocytes with a first polar body. In the pronuclear stage, the rate of oocytes with two pronuclei and a second polar body (21.4%) in the sperm and SE (0.04 mg/mL) injection group was significantly higher (P < 0.05) compared to other groups. The rate of 2-4-cell stage in sperm and SE (0.04 mg/mL) injection group was 38.1%, and it was significantly higher than that in the sperm injection group (22.9%). The rate of blastocyst stage in sperm and SE (0.04 mg/mL) injection group was 21.4%, the value was significantly higher than those in SE (0.08 mg/mL) injection group (0%), sperm injection group (5.7%), and sperm and SE (0.08 mg/mL) injection group (2.6%). These results suggest that SE induces activation of porcine oocytes and their further embryonic development, and that SE is effective for porcine ICSI.

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