Hydrostatic Pressure Affects In Vitro Maturation of Oocytes and Follicles and Increases Granulosa Cell Death

OBJECTIVE This study examines the effects of hydrostatic pressure on in vitro maturation (IVM) of oocytes derived from in vitro grown follicles. MATERIALS AND METHODS In this experimental study, preantral follicles were isolated from 12-day-old female NMRI mice. Each follicle was cultured individually in Alpha Minimal Essential Medium (α-MEM) under mineral oil for 12 days. Then, follicles were induced for IVM and divided into two groups, control and experiment. In the experiment group follicles were subjected to 20 mmHg pressure for 30 minutes and cultured for 24-48 hours. We assessed for viability and IVM of the oocytes. The percentage of apoptosis in cumulus cells was determined by the TUNEL assay. A comparison between groups was made using the student's t test. RESULTS The percentage of metaphase II oocytes (MII) increased in hydrostatic pressuretreated follicles compared to controls (p<0.05). Cumulus cell viability reduced in hydrostatic pressure-treated follicles compared to controls (p<0.05). Exposure of follicles to pressure increased apoptosis in cumulus cells compared to controls (p<0.05). CONCLUSION Hydrostatic pressure, by inducing apoptosis in cumulus cells, participates in the cumulus oocyte coupled relationship with oocyte maturation.