Effects of Different Electrical Stimulation Parameters and Cytochalasin B Treatment on Parthenogenetical Development of Porcine Oocytes

Oocytes were collected from porcine ovaries, cultured in vitro for 42-44 h, and cumulus cells were removed from oocytes. Matured oocytes were selected for parthenogenetical activation. The effect of different field strengths (FSs), pulse durations (PDs), electrical pulse numbers (EPNs), and the influence of cytochalasin B treatment on development of parthenogenetically activated porcine oocytes were investigated. In the first experiment, 4 different PDs (80,100,120,140 μs) were applied with a single or two 0.8 kV·cm^-1 pulse(s) to activate the oocytes. The results showed that a single 100 μs pulse of 0.8 kV/cm resulted in the highest blastocyst rate of (42.22±5.38)%, but it was not statistically different from the blastocyst rates of other groups (P＞0.05). In the second experiment, 4 different FSs (0.8,1.0,1.2,1.4 kV·cm^-1) were used with a single or two 100 μs pulse(s) to stimulate the oocytes. The highest blastocyst rate ［(44.04±0.68)%］ was observed in the group applied with single 100 μs pulse of 1.4 kV·cm^-1, but it was not statistically different from the blastocyst rates of other groups (P＞0.05). In the third experiment, 4 different PDs (80,100,120,140 μs) were used with a single 0.8kV·cm^-1 or 1.4 kV·cm^-1 pulses to activate the oocytes. The blastocyst rate of the group treated with a single 80 μs pulse of 1.4 kV·cm^-1 reached (54.60±2.86)%, which was significantly higher than that of other groups (P＜0.01). In the fourth experiment, one group of oocytes was stimulated only by a single 80 μs pulses of 1.4 kV·cm^-1, while the other groups was activated with a single 80 μs pulses of 1.4 kV·cm^-1 followed by 4 h-cytochalasin B treatment. The results indicated that the blastocyst rate of the latter group was (54.07±3.12)%, significantly higher than that of the former group (P＜0.01). The above results suggested that EPN had no significant effect on parthenogenetical development of porcine oocytes, and 4 h-cytochalasin B treatment to the oocytes after the electrical stimulation by a single 80 μs pulses of 1.4 kV·cm^-1 resulted in a high parthenogenetical blastocyst rate.