SIMULTANEOUS INJECTION OF ROUND SPERMATID NUCLEI FROM MICE AND HAMSTER OSCILLOGEN CAN INITIATE THE NORMAL DEVELOPMENT OF MOUSE EMBRYOS

PURPOSE: In the mouse, mature oocytes that have been injected with spermatid nuclei failed to become activated. Additional stimulation is required to trigger activation of the oocytes that leads to embryo development. This study was performed to determine whether simultaneous injection of mouse round spermatids and hamster oscillogen can fertilize oocytes and contribute to normal embryo development. MATERIALS AND METHODS: We simultaneously injected mouse oocytes with mouse round spermatid nuclei and a preparation of oocyte-activating protein (oscillogen) from hamster spermatozoa and compared the results with those of injection of testicular spermatozoa. RESULTS: The incidence of normal fertilization and embryo development after simultaneous injection of round spermatid nuclei and hamster oscillogen was not significantly different from that after the injection of testicular spermatozoa. Moreover, the rate of development of two-cell embryos to term did not differ very much between the two groups of oocytes. CONCLUSIONS: Simultaneous injection of round spermatid nuclei and oscillogen appears to be an ideal method for successful activation of oocytes by spermatid nuclei in vitro.