Objective To analyze the ultrastructural and Mitochondria DNA copies number of oocytes from women with polycystic ovary syndrome in vitro fertilization- embryo transfer, and to explore the reasons for the decline of oocyte quality in PCOS patients. Methods According to clinical data, 115 women, who received ICSI cycles due to male factors, were enrolled in this study, including 57 PCOS patients and 58 age-matched controls. All patients received controlled ovarian stimulation using standard long stimulation protocol, and 187 oocytes in total were collected for ultrastructural analysis using transmission electron microscopy and detection of mtDNA copies number using real time PCR. From PCOS oocytes, 52 were used for ultrastructural observation, and another 38 were used for mtDNA copy number detection. Meanwhile, 57 were used for ultrastructural observation and 40 for mtDNA copy number detection respectively in control oocytes. Ultrastructure of oocytes from the test and the control group:zona pellucida, perivitelline space, microvilli, cortical granules, Golgi body and endoplasmic reticulum morphology and distribution, mitochondria structure and quantity. Results No difference was detected in the ultrastructure of zona pellucida, perivitelline space, microvilli, cortical granules, Golgi body and endoplasmic reticulum in PCOS and control oocytes. However, the percentage of abnormal mitochondria in the cytoplasm of PCOS oocytes increased significantly (PCOS oocytes 58.7% vs control oocytes 17.7%, P<0.05), while the total number of mitochondria decreased significantly (PCOS oocytes 44.3±9.6/section vs control oocytes 65.4±12.7/section, P<0.05). Compared with control oocytes, mtDNA copies of PCOS oocytes decreased (PCOS oocytes54390 ±19139 vs control oocytes 88135 ±44235, P<0.05). Conclusion The alteration of percentage of abnormal mitochondria and number of mitochondria in PCOS patients might contribute to poor oocyte quality. |