Comparison of different treatments for parthenogenetic activation of bovine oocytes matured in vitro.

In vitro matured bovine oocytes were treated by three parthenogenetic activation methods. Basic treatment with Ca-ionophore and cytochalasin D was combined with cycloheximide (Group 2), electric impulse (Group 3), and cycloheximide and electric pulse (Group 1) treatments, respectively. Survival and the in vitro development of parthenogenetic embryos to hatched blastocyst stage were compared. Rates of the first cleavage and morula development significantly differed among the treatment groups. Further development rates of the treated embryos up to blastocyst stage did not differ. The best results were obtained by the combination of cycloheximide and electric treatments (Group 1; 14% blastocyst, 7% hatched blastocyst). The results suggest that the combined treatment for oocyte activation is the most efficient and should be applied for cloning procedures.