Abstract:
The current protocols used to activate pig nuclear transfer embryos are lessefficient than those used for other species. To address this problem, theeffect of multiple sets of electrical pulses on the parthenogeneticdevelopment of in vivo- andin vitro-derived porcine oocytes was examined. Each setof pulses consisted of two 1.5 kV cm<emph type="7">-1 DC pulsesof 60 s duration each, administered 1 s apart. Forin vivo-derived oocytes, application of a second set ofpulses 30 min after the first set increased the proportion of oocytes thatdeveloped to the blastocyst stage compared with a single treatment (51v. 34%). Application of a third set of pulses 30min after the second set reduced the rate of blastocyst formation comparedwith two sets of pulses. In contrast, the rate of blastocyst formation wasgreater with one set of pulses compared with two sets for in vitro maturedoocytes (31 v. 16%). Additional sets ofelectrical pulses did not affect the number of cells in blastocysts obtainedfrom either group of oocytes compared with a single treatment. In summary, thestudy demonstrates that the application of a second set of activating pulses30 min after the first set is beneficial toin vivo-derived oocytes, but detrimental toin vitro matured oocytes, in terms of their ability todevelop parthenogenetically to the blastocyst stage.