Investigation of Cell Death in Cumulus and Oocyte Complex (COCs) of Preovulatory Follicle Produced In Vitro after Exposure to Hydrostatic Pressure

Rashidi Z *, Azadbakht M , Amini A ,


Objective: In vitro maturation of oocytes is a safe and effective treatment offered in some fertility centers for assisted reproduction. Cumulus cells play a critical role in oocyte maturation and fertilization. Whether the degree of cell death in the cumulus–oocyte complex (COCs) has an impact on oocyte development potential is unclear. Physical forces may to assure the incidence of cell death in (COCs). Hydrostatic pressure as a physical force is effective in reproductive system and there is an increase in intrafollicular pressure between 15-20 mmHg in the ovulating follicle during the late stage of the ovulatory process and COCs to expose intrafollicular pressure in preovulatory follicle. In this study we examined the effects of hydrostatic pressure on the viability of COCs derived from preovulatory follicle produced in vitro. Materials and Methods: Preantral follicles were isolated from 12-day-old female NMRI mice each follicle cultured individually in micro<font>drop</font>s 20 μl of MEM-α culture medium supplemented with 5% fetal bovine serum 100 mIU/ml recombinant follicle stimulating hormone (Gonal-f) 10ng/ml recombinant epidermal growth factor under detoxified mineral oil for 12 days. On day 12 follicles with diameter nearly 500 µm and good quality were induced using 7.5 IU/ml human chorionic gonadotropin for in vitro maturation. At the start of maturation period follicles divided into two groups; control and experiment. In experiment group follicles were transferred to pressure chamber and subjected to 20 mmHg hydrostatic pressure for 30 min and then follicles from two groups were cultured for 24-48 h. Viability of cumulus cells and oocyte were assessed with nuclear differential staining (propidium iodide & bisbenzimide) on 0 and 24 h after culture. Results: Our results indicate that viability of the cumulus cells were reduced in hydrostatic pressure treated follicles compared to control (p