Parthenogenetic activation of cattle follicular oocytes in vitro with ethanol

Cattle follicular oocytes cultured in vitro for 24-33 h were treated with ethanol to induce artificial activation. When oocytes were cultured for 27-33 h before ethanol treatment, 60-68% of oocytes were activated and were found to have a female pronucleus(ei). In contrast, maturation culture of oocytes for 24-26 h resulted in low activation rates (25-38%). The female pronucleus was formed in the activated oocytes within 8-10 h of incubation after ethanol treatment. And it became visible under interference-contrast microscope by centrifugation for 3 min at 15,000g and 10 min at 20,000g. These results indicate that ethanol treatment is effective for activation of cattle follicular oocytes and that the pronucleus formed in the activated oocyte can be visualized by centrifugation.