Blastocyst formation in vitrified-warmed preimplantation embryos derived from vitrified-warmed oocytes in a mouse model

• Published in: Clinical and experimental reproductive medicine Vol. 51; no. 1; pp. 57 - 62
• Main Authors: Hong, Yeon Hee, Jee, Byung Chul
• Format: Journal Article
• Language: English
• Published: Korea (South) Korean Society for Reproductive Medicine 01.03.2024; 대한생식의학회
• Subjects: Original; 산부인과학; Embryo; Cryopreservation; Vitrification; Oocytes; Blastocyst
• ISSN: 2233-8233; 2233-8241
• DOI: 10.5653/cerm.2023.06499

Objective: The purpose of this study was to use a mouse model to investigate the blastocyst formation rate in vitrified-warmed embryos derived from vitrified-warmed oocytes. Methods: Metaphase II oocytes obtained from BDF1 mice were vitrified and warmed, followed by fertilization with epididymal sperm. On day 3, a total of 176 embryos, at either the eight-cell or the morula stage, were vitrified-warmed (representing group 1). For group 2, 155 embryos at the same developmental stages were not vitrified, but rather were directly cultured until day 5. Finally, group 3 included day-5 blastocysts derived from fresh oocytes, which served as fresh controls. The primary outcome measured was the rate of blastocyst formation per day-3 embryo at the eight-cell or morula stage.Results: The rates of blastocyst formation per day-3 embryo were comparable between groups 1 and 2, at 64.5% and 69.7%, respectively (p>0.05). The formation rates of good-quality blastocysts (expanded, hatching, or hatched) were also similar for groups 1 and 2, at 35.5% and 43.2%, respectively (p>0.05). For the fresh oocytes (group 3), the blastocyst formation rate was 75.5%, which was similar to groups 1 and 2. However, the rate of good-quality blastocyst formation in group 3 was 57.3%, significantly exceeding those of group 1 (p=0.001) and group 2 (p=0.023).Conclusion: Regarding developmental potential to the blastocyst stage, vitrified-warmed day-3 embryos originating from vitrified-warmed oocytes demonstrated comparable results to non-vitrified embryos from similar oocytes. These findings indicate that day-3 embryos derived from vitrified-warmed oocytes can be effectively cryopreserved without incurring cellular damage.