Abstract: Objective: To explore the effect of cryopreservation on the mitochondrial DNA（ｍｔＤＮＡ） deletions and energy metabolism of human oocyte, so as to investigate the effect of cryopreservation on oocytes preservation. Methods: The dumped oocytes with 0PN, 2PN and 3PN during routine IVF were collected for this cryopreservation study. Those oocytes were randomly divided into two groups, one for vitrification cryopreservation （Ｇｒｏｕｐ Ａ） and the other as control （Group B, without cryopreservation）. The nested polymerase chain reaction （ＰＣＲ） was used to detect the mtDNA deletions of oocyte mtDNA before and after cryopreservation. Real-time quantitative PCR was adopted to determine the copy number of oocyte mtDNA. ATP contents were detected using luciferin-luciferase assays. Results: There were not significant differences in the mutation frequency of oocyte mtDNA deletions and the copy number of mtDNA between two groups（P＞0.05）. However, The ATP content in the group A was significantly lower than that in the group B. Conclusions: The effect of cryopreservation on the oocyte mtDNA deletions and the copy number of mtDNA was limited, suggesting that cryopreservation can be properly used to preserve oocyte.

Key words: Cryopreservation, Oocytes, DNA, mitochondrial, Oxidative stress