P-28: Hydrostatic Pressure Induced Cell Deathin Cumulus Cells and Improved In vitro Maturationof Oocytes from Preovulatory Follicles

Background: Cryopreservation of ovaries is an important technique in assisted reproduction technology. Physical forces like hydrostatic pressure have a pivotal role in reproduction systems. Due to changes in intrafollicular pressure during ovulatory process, this study designed to examine the effects of hydrostatic pressure on oocyte maturation and cell death in cumulus cells from cryopreserved ovary. Materials and Methods: Ovaries obtained from matured balb/c mice and cryopreserved in ethylene glycoland DMSO in MEM-α with FBS in straw. Preovulatory follicles isolated from frozen/thawed and fresh ovarian tissues, divided into pressure positive (PP) and pressure negative (PN) groups. In PP groups, follicles were subjected to 20 mmHg hydrostatic pressures for 30 minuets. Follicles were cultured in maturation medium for 24h and then assessed for in vitro maturation of oocyte. Viability of cumulus cells and oocyte were assessed with nuclear differential staining. TUNEL assay was used to detect apoptosis in cumulus cells. Results: Oocyte maturation and cell death in cumulus cells were increased in PP groups and viability of cumulus cells was decreased significantly. Hydrostatic pressure also didn’t changed viability of oocyte in all groups. Conclusion: Hydrostatic pressure had the mild effect on cell death incidence in cumulus cells without negative effect on oocyte viability. It can be used to improve oocyte maturation in fresh and frozen ovaries.