P-29: Effects of Cumulus Cells on Survival, In vitro Maturation,Fertilization and Subsequent Developmental Capacity of Mouse Germinal Vesicle Stage Oocytes during Vitrification

Background: Cryopreservation of oocytes, which is an interesting procedure to conserve female gametes, is an essential part of reproductive biotechnology. The objective of the present study was to investigate the effects of cumulus cells on survival,in vitro maturation,fertilization and subsequent developmental capacity of mouse germinal vesicle stage oocytes during vitrification. Materials and Methods: Immature oocytes (germinal vesicles) with and without cumulus cells isolated from ovaries of normal mice(4-6W of age) were either vitrified in conventional straw using 15% ethylene glycol,15% dimethyl sulfoxide and 0.5M sucrose as vitrification solution or exposed to vitrification solution without subjected to liquid nitrogen. After warming, oocytes were investigated for nuclear maturation following in vitro maturation and for developmental capacity to blasetocyst following in vitro fertilization. Fresh immature oocytes were used as the control group. Results: Fertilization and development to blasetocyst rates in vitrified oocytes with cumulus cells were significantly lower than control group (p<0.05). Present of cumulus cells in all experiments and control groups significantly increased fertilization rate than denuded oocytes (p<0.05). Also in vitrified groups survival rate of oocytes that vitrified with cumulus cells was significantly higher than denuded oocytes (p<0.05). Conclusion: Germinal vesicle stage oocytes in present or absent of cumulus cells can be vitrified successfully.Present of cumulus cells can be increase the fertilization rate in IVF procedure. also cumulus cells have a protective role during vitrification of germinal vesicle stage oocytes.