|
The present study was undertaken to determine the optimal condition for parthenogenetic activation of rabbit oocytes by electric stimulation in vitro in an attempt to develop nuclear transplantation techniques for cloning mammalian embryos and animals. Freshly ovulated oocytes were collected from superovulated rabbits from 13 to 26 hrs. after hCG injection. The cumulus-free oocytes were activated parthenogetically by repeated stimuli of square direct electric pulses in O.3M mannitol solution. After applying electric stimulations of different voltages, pulse durations and pulse times, all of the oocytes were cultured in TCM-199 with 10% FCS for 96 hours in a 5% CO₂ incubator, and their developmental potential in vitro was examined. The higher activation rate (68.9%) was achieved at the voltage of 2.0kv/cm, the pulse duration of 60 μsec and three pulse times and the activation rate of 100% was achieved at the pulse duration of 100 and 200 μsec, the voltage of 1.5kv/cm and three pulse times. Although the higher rates of activation of oocytes were achieved at 100 and 200 μsec, none of them developed to blastocyst in vitro. The oocytes collected 18~20 hours post hCG injection showed the highest rate of activation and development to blastocyst in vitro than the oocytes collected 13~15 or 25~26 hours post hCG injection. Therefore, it can be suggested that the application of electric stimulation of 2.0kv/cm, 60 μsec and three pulse times to the oocytes collected at 18~20 hours post hCG injection would be more beneficial for the parthenogenetic activation of oocytes in rabbits.
|