Maternal-Effect Gene Expression in Cultured Preantral Follicles Derived from Vitrified-Warmed Mouse Ovary

OBJECTIVE This study was conducted to assess survival of follicles, their oocyte maturation and fertilization potential as well as expression of early embryo developmental genes in in vitro cultured pre-antral follicles derived from vitrified-warmed mouse ovary. MATERIALS AND METHODS In this experimental study, ovaries of 12-day old Naval Medical Research Institute (NMRI) female mice were placed into non-vitrified and vitrifiedwarmed groups. Isolated preantral follicles from experimental groups were cultured in vitro for 12 days. On the 12(th) day of culture, oocyte maturation was induced and then matured oocytes were in vitro fertilized. The rates of oocyte maturation and two-cell stage embryo formation were assessed. Relative expression of Mater and Zar1 was evaluated on days 1, 6, 10 and 12 of culture. Data analysis was performed by t test and two-way ANOVA (P<0.05). RESULTS Our data showed no significant difference between the control and vitrification groups in the rate of follicular survival, oocyte maturation and two-cell stage embryo formation. The level of gene expression was higher on the 6(th)and 10(th)days of culture for Mater and Zar1 in vitrified-warmed group compared with non-vitrified group, however, there was no significant difference between the two groups. CONCLUSION It seems that the applied vitrification method did not reveal any negative effect on maturation and developmental competence of oocytes surrounded in preantral follicles and therefore could preserve follicular reserves efficiently.