Assisted Activation of Electrical Stimulation on Human Mature Oocytes

[Objective] To observe activation effects of electrical stimulation on human mature oocytes. [ Methods ] Oocytes with different ages were divided into four groups. Forty-nine fresh oocytes after vitro maturation were obtained in group A. In group B unfertilized culture-aged oocytes after conventional in vitro fertilization were recruited ( n - 42). Fifty-seven unfertilized oocytes after ICSI were included in group C. And in group D unfertilized oocytes after 48 hours culture in. vitro were collected ( n = 37). All oocytes were stimulated two times with direct current pulse. Oocyte activation and embryo development were observed. [Results] Activation rate in group A was 42. 9% (21/49), significantly lower than that in group B, group C, and group D (69.0% -75.4%, P 0. 05). Two thirds of activated oocytes ( n = 21) in group A displayed one pronuclear (PN) and two polar bodies (PB) (1PN + 2PB) . In contrast in group C and group D oocytes with two pro nuclei and two polar bodies (2PN + 2PB) were found as the predominant pattern. The cleavage rates in group A, group B, and group C were 81.0% (17/21), 82.8% (24/29) and 88.4% (38/43) respectively, much higher than that in group D (19. 2%, 5/26) (P 0.01). On the third day after electrical stimulation, 17.6% (3/ 17), 29.2% (7/24), 31.4% (11/35) of activated oocytes progressed to 8-cell stage respectively in group A, group B and group C. [Conclusion] Human oocytes at different ages can be effectively activated by electrical stimulation, with different activation patterns and embryo development. As an effec- tive activation method, direct current pulse may be used to assist fertilization .