Effect of Ethanol on Maturation and Development of Immatur Mouse Oocytes

Purpose: To study the effect of ethanol on resumption of meiosis, maturation and development of immature mouse oocytes in vitro. Materials and Methods: Immature oocytes were dissected from ovary of NMRI strain mouse (6-8 weeks old) and divided into control and experimental groups. The absolute ethanol was imposed to oocytes at doses of 0 (Control), 0.05, 0.1, 0.2 and 0.4% (v/v) in maturation culture medium (MEM- + 100 mlIU/ml rFSH + 7.5 IU/ml hCG + 5% FCS). After 24 hours the matured oocytes were fertilized with spermatozoa in T6 medium and cultured for 5 days. Maturation and embryo formation observed by invert microscope and the results were considered as categorical variables with Chi- Square tests. Results: The percentage of resumption of meiosis and Metaphase II (MII) in control and the four experimental groups were 76.18%, 84.81%, 83.10%, 74.54%, 78.93% and 60.98%, 71.79%, 68.17%, 60.08%, 64.52%, respectively The percentage of the oocytes remained at the Germinal Vesicle (GV) stage were higher in 0.2 % (v/v) ethanol than the other groups (23.8%, 15.1%, 16.8%, 25.4%, 21%). The rate of resumption of meiosis and maturation mouse oocytes between control and experimental groups in 0.05 % (v/v) ethanol (P<0.001) and 0.1 % (v/v) ethanol (P<0.05) were significantly different. At 2-cell stage the rate of embryo formation between control and experimental groups in 0.2 and 0.4 %( v/v) ethanol were significantly different (P<0.001). Conclusions: The present study indicates that 0.05% (v/v) ethanol as solvent during in vitro culture media has positive effects on in vitro maturation of immature mouse oocytes, but same effects on embryonic development has not been detected. In conclusion it has not an inhibitory effect on embryonic development.