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Abstract Purpose The aim of the present study was to investigate the effect of glutathione ethyl ester (GSH‐OEt) in the recovery medium on the developmental competence of mouse vitrified‐warmed MII oocytes. Methods Vitrified‐warmed oocytes were incubated for 1 h in recovery medium in the presence or absence of 0.5 mM GSH‐OEt. The authors examined the effects of GSH‐OEt, first on the levels of glutathione (GSH) and reactive oxygen species (ROS) in vitrified‐warmed oocytes, and second, on in vitro blastocyst development, division speed to blastocysts, and total cell numbers of blastocysts from vitrified‐warmed oocytes fertilized by Intracytoplasmic sperm injection (ICSI). Results Adding GSH‐OEt to the recovery medium significantly (p

Abstract Purpose To investigate the first‐division kinetics and in vitro development of embryos produced by injecting sonicated sperm heads with high or low chromosomal integrity into oocytes. Methods Mouse spermatozoa were frozen after separating the sperm heads from the tails by sonication in an EGTA solution (EGTA group) or M2 medium (M2 group). The chromosomal integrity of sonicated mouse spermatozoa was analyzed by injecting the sperm heads into fresh mouse oocytes. The developmental potential of spermatozoa was examined by injecting the sperm heads into vitrified‐warming mouse oocytes. We used a time‐lapse monitoring system to compare the first‐division kinetics. Results Chromosomal integrity was preserved significantly more frequently in the EGTA group (90.6%) than in the M2 group (32.7%). Blastocysts developed significantly more often in the EGTA group (80.8%) than in the M2 group (39.6%). In the M2 group, with frequent chromosome aberrations, the time between the sperm injection and first cleavage was delayed (18.4 hours), compared to the EGTA group (16.5 hours). All results of the EGTA group were similar to that of fresh epididymal spermatozoa. Conclusion The EGTA solution for sonication maintained the integrity of sperm chromosomes. Our results revealed a relationship between sperm chromosome integrity and first‐division kinetics.

Abstract Purpose The time‐lapse system is a device that allows continuous monitoring without removing embryos from the incubator. Using a time‐lapse system, we retrospectively investigated cleavage speed time points as potential indicators for selecting high‐quality viable blastocysts. Methods This study included 963 zygotes of two pronuclei retrieved from 196 patients between January 2015 and December 2016. All embryos in culture were monitored by time‐lapse after intracytoplasmic sperm injection. Of 492 blastocysts developed in vitro, 128 vitrified‐warmed single blastocyst transfers were classified into pregnancy and non‐pregnancy groups, and the parameters were compared. Results In the pregnancy group, timing of both morula compaction and regular blastocyst formation was significantly faster than in the non‐pregnancy group. Furthermore, the optimal cutoff values for compacted morula (94.9 hours) and regular blastocyst (113.9 hours) were determined using the receiver operator characteristic curve analysis. Embryos that formed compacted morulae within 94.9 hours and developed into regular blastocysts within 113.9 hours were associated with a significantly higher pregnancy rate than those that did not (44.4% vs 16.0%). Conclusion The timing of morula compaction and regular blastocyst formation is important as an indicator of high‐quality blastocysts to increase odds for pregnancy after embryo transfer.