Prediction of the in vitro developmental competence of early‐cleavage‐stage human embryos with time‐lapse imaging and oxygen consumption rate measurement

Abstract Purpose To assess an embryo's ability to develop into a good‐quality blastocyst during the early‐cleavage stage using time‐lapse imaging and the oxygen consumption rate. Methods In total, 942 zygotes had their oxygen consumption rates measured. In total, 282 zygotes were assessed by using time‐lapse imaging. In total, 121 zygotes were examined by using both their oxygen consumption rate and time‐lapse imaging. Results The embryos with moderate respiration rates of between 0.41 and 0.61 (×1014/mol s−1) on day 3 had a 22.1% chance of becoming good‐quality blastocysts; those outside that range had a 14.3% chance. With the time‐lapse system, when the first division was within 24 hours, 22.3% of the embryos grew to good blastocysts. After 24 hours, the rate dropped to 8.6%. The intervals between two consecutive cleavages were calculated and the duration of the second cell cycle was defined. When the time was between nine hours and 13 hours, there was a higher rate of good blastocysts. Regarding both criteria, when the embryos had progressed in the optimal range, a high percentage of them had become good blastocysts; it was 8.0% outside of that range. Conclusion Individual embryos with the potential to develop into good‐quality blastocysts could be selected at day 3 of culture using these systems

Effects of cyclophosphamide administration on the in vitro fertilization of mice

Abstract Purpose To evaluate the oocyte fertilization ability and embryo growth after cyclophosphamide (CPA) treatment in mice. Methods Mice were treated with CPA at different doses (0‐800 mg/kg body weight). The oocytes then were retrieved and evaluated for their in vitro fertilization efficiency. Results The average number of metaphase II (MII) oocytes significantly decreased by ≥400 mg/kg CPA administration. The fertilization rate also decreased in the group that was treated with ≥400 mg/kg CPA. However, after fertilization, the embryos demonstrated normal growth ability. Two weeks after CPA administration, the number of mice from which the oocytes could be retrieved markedly decreased, but the fertilization rate and development of morphological features in the embryos were similar to those of the controls. One month after CPA administration, the number of mice from which the oocytes could be retrieved, fertilization rate, and development of the morphological features in the embryos were similar to those of the controls. Conclusion The number of oocytes decreased as the CPA administration level increased; however, the oocytes' potential for fertilization and development to the blastocyst stage was not significantly affected. One month after CPA administration, the number of oocytes and the potential for development into blastocysts were recovered