Human sperm cannot fertilize oocytes immediately upon ejaculation, but must acquire the ability to bind and penetrate the zona pellucida. Hyperactivation, which is linked to the process of capacitation, is a vigorous pattern of sperm motility marked by wide-amplitude, high-velocity, whiplash movements of the flagellum. This study was performed to investigate the correlation between hyperactivated (HA) motility patterns assessed by computer-aided sperm analysis (CASA) and the fertilization rate (FR) in vitro. Swim-up sperm were collected in 135 IVF cycles with at least 3 oocytes collected. Because no cases satisfied the HA motility pattern of "Star-spin", patients were divided into 3 groups: Sperm with curvilinear velocity (VCL) ≥ 100 μM/sec, linearity (LIN) < 60% and amplitude of lateral head displacement (ALH) ≥ 5 μM were "All HA". Sperm with straight-line velocity (VSL) ≥ 40 μM/sec, LIN ≥ 60% and ALH < 5 μM were "Non-HA". Others were defined as "Transition phase". The FRs in 81 "All HA" cycles, 33 "Non-HA" cycles, and 21 "Transition phase" cycles were 79.5 ± 26.6%, 65.4 ± 32.5%, and 80.8 ± 27.3% respectively. There was a significant difference between "All HA" and "Non-HA" cycles in the FRs (P=0.018). In 27 (20.0%) of 135 IVF cycles, the FRs were ≤ 50% ("poor" group). Eleven (13.6%) of 81 "All HA" cycles, 12 (36.3%) of 33 "Non-HA" cycles, and 4 of 21 "Transition phase" cycles belonged to the "poor" group. There was a significant difference between "All HA" and "Non-HA" cycles (P=0.006) in these incidences. The better FRs were obtained in patients with "All HA" cycles, and lower FRs were obtained in those with "Non-HA" cycles. These findings suggest that the assessment of HA motility patterns by means of CASA could be one of the predictors of human sperm fertilizing ability.

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Intracytoplasmic Sperm Injection (ICSI) has been widely applied for curing human infertility. In this study the developmental potential of Japanese monkey embryos produced by ICSI is reported in a practically relevant system. Oocytes retrieved by laparoscopy from follicles in ovaries of gonadotrophin-stimulated fertile females were fertilized by ICSI using spermatozoa obtained from a fertile male. An additional chemical stimulus was not necessary to achieve oocyte activation with pronuclear formation after ICSI. Successful fertilization was confirmed by extrusion of the second polar body and the presence of both male and female pronuclei at 18-20 h post-ICSI. Some two-cell stage embryos obtained by ICSI were transferred to synchronous recipients and the others were cultured in CMRL medium for 168 h to assess their developmental competence. Oocytes collected laparoscopically from hyper-stimulated monkey ovaries were fertilized by ICSI and completed preimplantation development in vitro, however no pregnancy was confirmed after embryo transfer. This study demonstrates for the first time that the oocytes of the Japanese monkey are able to support advanced embryonic preimplantation development in vitro. It is suggested that the Japanese monkey is an excellent preclinical model for examining and understanding many aspects of ICSI for endangered primates.

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Conjoined twins result from an abnormal process in the development of monozygotic twins. Monozygotic twins are closely associated with assisted reproductive technology, especially assisted hatching. The prognosis for conjoined twins is very poor. This risk underscores the importance of fetal screening by ultrasonography in the early stages of pregnancy, since the conjoined twin can be detected by ultrasonography. Here we reported a case of conjoined twin in a triplet pregnancy after a transfer of cryopreserved embryos with assisted hatching that were obtained by ICSI.

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