Iranian

Background: Leukemia inhibitory factor (LIF) is a pleiotropic cytokine of interleukin-6 family with a remarkable range of biological actions such as proliferative effects on the granulosa and theca cells. The aim of this study was to evaluate the effects of LIF on the growth and maturation of mouse fresh and vitrified preantral follicles, an in vitro model was developed. Methods: The ovaries of 14-day-old mice were vitrified in a mixture of ethylene glycol, ficoll 70 and sucrose in PB1 for 5 min. The preantral follicles were mechanically isolated from vitrified-warmed and non-vitrified ovaries. They were cultured in α-minimum essential medium supplemented with 5% fetal bovine serum, 100 mIU/ml recombinant follicle stimulating hormone, 1% insulin, transferrin and selenium, 20 ng/ml murine recombinant epidermal growth factor and different concentrations of LIF (25, 50, 100 ng/ml) for 12 days. On day 12, ovulation was induced using 1.5 mIU/ml human chorionic gonadotropin. In this study, the follicle diameter, survival rate and maturation rate were assessed. Results: The mean diameter of fresh and vitrified preantral follicles cultured in 50 ng/ml concentration of murine recombinant LIF was significantly higher than that of other concentrations in each group on day 2 (229.42 ± 30.40, 222.55 ± 33.4) (P<0.001) and on day 4 (340.45 ± 61.05, 299.50 ± 65.55), respectively (P<0.01). The survival rates of follicle in fresh and vitrified groups were 80.56% and 77.78, respectively. There was no significant difference between control and treated groups. The percentage of follicles which released metaphase II (MII( oocyte in fresh groups in the presence of 0, 25, 50, 100 ng/ml of LIF was 16%, 14.28%, 40% and 21.05% (P<0.01) and so in vitrified groups were 11.76%, 14.28%, 28.57% and 13.38%, respectively (P<0.05). There were significant differences between 50 ng/ml LIF-treated groups with other concentrations in each group. Conclusion: Therefore, in vitro growth and maturation of mouse preantral follicles were improved in the presence of 50 ng/ml LIF.