In cases of testicular sperm extraction sperm aspiration and severe oligozoospermia for which intracytoplasmic sperm injection (ICSI) is indicated, there are cases where motile sperm are difficult to obtain even from collected semen. In cases when little or no motile sperm is obtainable from prepared sperm suspension. We stimulated sperm motility using pentoxifylline and then selected live sperm. The clinical outcomes of recovery of live sperm were compared with cases in which motile sperm was obtainable. Fertilization and embryo recovery rates of the pentoxifylline group were significantly lower than those of the control group. However, the pregnancy, implantation, and abortion rates of the pentoxifylline group were not significantly different from those of the control group, suggesting a favorable outcome if a viable embryo is implanted. Moreover, no abnormal findings were found in babies subsequently born. Considering that the important point of ICSI is to inject live sperm, pentoxifylline treatment was effective in cases where sperm sorting was difficult.

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The present study focused on the level of Sr²⁺ activation required by mouse oocytes in round spermatid injection (ROSI) and analyzed the resultant embryos cytogenetically at the first cleavage and blastocyst stages. Mouse oocytes were divided into 3 groups: Group A, oocytes treated by activation using Sr²⁺ for 40 min before ROSI; Group B, oocytes treated by activation using Sr²⁺ for 1 h after ROSI; and Group C, oocytes treated by activation using Sr²⁺ for 5 h after ROSI. One round spermatid obtained from mature RFM/Ms-Rb(6.15) males was injected into each oocyte individually. The fertilization rate of oocytes in ROSI, the development rate of zygotes to the blastocyst stage and chromosomal normality in the resultant embryos were highest in Group A, suggesting activation using Sr²⁺ for 40 min before ROSI as the most appropriate treatment. At the first cleavage, many kinds of male-derived abnormalities, such as asynchrony and constitutive chromosome abnormalities etc., were observed in all groups. At the blastocyst stage, many parthenogenetic embryos, showing n, 2n and 2n/n with no translocated chromosome, were typically observed in all groups. Normal offspring were obtained by embryo transfer of the blastocysts derived from Group A, and their fertility after sexual maturity was confirmed by mating.

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