Abstract
More than half of unfertilized oocytes after ICSI failed to activate in human subjects. We investigated whether the fertilization rate after ICSI can be increased by electrical stimulation. At first, the effects of electrical stimulation on the parthenogenesis of hamster oocytes were investigated. Delivering a single 375 V/cm DC pulse for 100 μsec was effective in inducing parthenogenesis. The pattern of Ca2+ transient increase in hamster oocytes induced by electrical stimulation was recorded with Indo-1/AM. It seemed that a single sharp increase in Ca2+ initiated parthenogenetic activation. Secondly, a 375 V/cm pulse was applied to human oocytes after ICSI. In the case of immotile sperm, the fertilization rate and cleavage rate were increased significantly by electrical stimulation. On the other hand, in the case of motile sperm, no increase in the fertilization rate was observed. This study demonstrated that electrical stimulation combined with ICSI may be expected to contribute to increasing the fertilization rate in the case of immotile sperm.
