BACKGROUND: The polycystic ovary syndrome (PCOS) is a substantial obstacle to female fertility due to ovulation inhibition. Oocyte cryopreservation is crucial for preserving fertility in women with fertility-compromising disorders such as PCOS. OBJECTIVE: In this study, the ultrastructural damages of oocytes were evaluated following freezing from PCOS mouse model. MATERIALS AND METHODS: This experimental study was conducted on 30 adult NMRI mouse. The study comprised three groups: 1) unfrozen PCOS oocytes
2) vitrified-thawed control oocytes
and 3) vitrified-thawed PCOS oocytes. Transmission electron microscopy was employed for ultrastructure examination across all groups. Moreover, the expression of apoptotic genes, including BAX and Bcl2, was assessed using real time-quantitative polymerase chain reaction (RT-PCR). RESULTS: The oocyte cryopreservation process had a high impact on the destruction of ooplasm cortical granules, Golgi complexes and mitochondria in vitrified-thawed PCOS oocytes compared to the other groups. In PCOS oocytes, particularly those that were vitrified-thawed, there was a notable increase in vacuolation, with a higher abundance of larger and more numerous vacuoles observed compared to the control group. The vitrified-thawed PCOS group also exhibited a notable increase in the expression of the apoptotic gene compared to the other groups (p <
0.05). CONCLUSION: A precise evaluation of oocyte cryopreservation is imperative for improving this technique and for producing high-quality oocytes with enhanced fertility potential. This study contributes valuable insights into understanding the intricate relationship between PCOS, cryopreservation and oocyte quality. https://doi.org/10.54680/fr25210110412.