Improved developmental potential of mouse vitrified‐warmed oocytes achieved by culturing in recovery medium with glutathione ethyl ester (GSH‐OEt)

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 < 0.05) increased GSH content and decreased ROS levels in vitrified‐warmed oocytes. The blastocyst rate did not differ significantly between the two groups, but the speed of development to blastocysts in the GSH‐OEt (+) group was significantly more rapid. In addition, the total blastocyst cell number was significantly higher in the GSH‐OEt (+) group than in the GSH‐OEt (−) group (92.8 ± 5.1 vs. 71.4 ± 3.5, p < 0.01). CONCLUSION: Adding GSH‐OEt to the recovery medium of vitrified‐warmed mouse oocytes enhances the development potential of oocytes and improves the quality of blastocysts.