Purpose The purpose of this study is to examine the clinical outcomes of blastocysts derived from human singlepronucleate (1PN) embryos after conventional in vitro fertilization (cIVF) and intracytoplasmic sperm injection (ICSI) cycles. Methods This was a retrospective study at a reproductive center of a hospital. To evaluate embryo quality and clinical outcomes, cIVF or ICSI cycles with one or more 1PN embryos were compared with same cycles with 2PN embryos (control cycles).Results A total of 623 cycles (426 cIVF cycles and 197 ICSI cycles) were treated with cIVF or ICSI. The single pronuclear status rate was similar between cIVF (22.1 %) and ICSI (25.1 %) cycles. Although the development rates of 1PN embryos on day 3 and day 5/6 in cIVF were significantly higher than those in ICSI, those of 1PN embryos in cIVF were significantly lower compared to 2PN embryos (p<0.01). Nonetheless, the ongoing pregnancy rates achieved with 1PN blastocysts in 1PN embryos did not significantly differ from the control group. Thirty-three transfer cycles with 33 blastocysts derived from 1PN embryos in cIVF resulted in nine deliveries with no newborn malformations; however, no implantation was observed in three ICSI cycles. Conclusion Although the blastocyst formation rate of 1PN embryos was significantly lower than 2PN embryos in cIVF and ICSI cycles, 1PN blastocysts in cIVF, and not from ICSI, demonstrated an adequate ongoing pregnancy rate. These results suggested that 1PN blastocysts in cIVF are available for clinical use and may lead to an increase in the chance of pregnancy in patients receiving assisted reproductive technology with 1PN embryos.

In this study the clinical and neo-natal outcomes after transfer of blastocysts derived from oocytes containing aggregates of smooth endoplasmic reticulum (SER) were compared between IVF and intracytoplasmic sperm injection (ICSI) cycles. Clinical and neo-natal outcomes of blastocysts in cycles with at least one SER metaphase II oocyte (SER + MII; SER + cycles) did not significantly differ between the two insemination methods. When SER + MII were cultured to day 5/6, fertilization, embryo cleavage and blastocyst rates were not significantly different between IVF and ICSI cycles. In vitrified-warmed blastocyst transfer cycles, the clinical pregnancy rates from SER + MII in IVF and ICSI did not significantly differ. In this study, 52 blastocysts (27 IVF and 25 ICSI) derived from SER + MII were transferred, yielding 15 newborns (5 IVF and 10 ICSI) and no malformations. Moreover, 300 blastocysts (175 IVF and 125 ICSI) derived from SER-MII were transferred, yielding 55 newborns (24 IVF and 31 ICSI cycles). Thus, blastocysts derived from SER + cycles exhibited an acceptable ongoing pregnancy rate after IVF (n = 125) or ICSI (n = 117) cycles. In conclusion, blastocysts from SER + MII in both IVF and ICSI cycles yield adequate ongoing pregnancy rates with neo-natal outcomes that do not differ from SER-MII.

In cases where GnRHa fails to trigger oocyte maturation, a rescue protocol entailing re-triggering with HCG can produce successful outcomes.

To culture preimplantation embryos in vitro, water-jacketed CO2 incubators are used widely for maintaining an optimal culture environment in terms of gas phase, temperature and humidity. We investigated the possibility of mouse embryo culture in a plastic bag kept at 37°C. Zygotes derived from in vitro fertilization or collected from naturally mated B6D2F1 female mice were put in a drop of medium on a plastic culture dish and then placed in a commercially available plastic bag. When these were placed in an oven under air at 37°C for 96 h, the rate of blastocyst development and the cell numbers of embryos decreased. However, when the concentration of O2 was reduced to 5% using a deoxidizing agent and a small oxygen meter, most zygotes developed into blastocysts. These blastocysts were judged normal according to their cell number, Oct3/4 and Cdx2 gene expression levels, the apoptosis rate and the potential for full-term development after embryo transfer to pseudopregnant recipients. Furthermore, using this system, normal offspring were obtained simply by keeping the bag on a warming plate. This culture method was applied successfully to both hybrid and inbred strains. In addition, because the developing embryos could be observed through the transparent wall of the bag, it was possible to capture time-lapse images of live embryos until the blastocyst stage without needing an expensive microscope-based incubation chamber. These results suggest that mouse zygotes are more resilient to their environment than generally believed. This method might prove useful in economical culture systems or for the international shipment of embryos.