Mitochondrial networks of cumulus cells and oocyte quality

BACKGROUND: Mitochondria play vital roles in oocyte functions and they are critical indicators of oocyte quality which is important for fertilization and development into viable offspring. Quality-compromised oocytes in which mitochondrial dysfunction plays a significant role are correlated with infertility, developmental disorders and embryo loss. A significant role in the oocytes of cytoplasmic accumulation and a sufficient amount of the mitochondrial pool of oocytes is played by the cumulus cells surrounding it.

AIM: to conduct a comparative analysis between the state of mitochondrial networks of cumulus cells and the quality of oocytes.

MATERIALS AND METHODS: The study included 22 women aged 28 to 37 years inclusive (mean age 32.3 ± 1.2 years) with tubal infertility. During the assisted reproductive technology procedures, 74 oocytes were obtained. 39 good quality oocytes and their cumulus cells were compared with 35 bad quality oocytes and their cumulus cells respectively. After puncture of ovarian follicles cumulus cells were isolated and stained with fluorescent dye for cell tracing and mitochondrial imaging in vivo. The method of confocal microscopy was used to analyze the three-dimensional organization of mitochondria in 20–30 cells of one pool of follicular fluid. The following parameters were used to evaluate the mitochondrial network: fluorescence decay time and fluorescence intensity.

RESULTS: The decay time of fluorescence in cumulus cells associated with a good quality oocyte was significantly higher (p = 0.032) than in the case of identification of oocytes with negative signs.

CONCLUSION: The structure of mitochondrial networks in cumulus cells correlates (r = 0.76) with the quality of oocytes.