Effect of Beta Mercaptaethanol with and without BSO [DL-Buthionine Sulfoximine] on Resumption of Meisosis, in vitro maturation and Embryo development of immature mouse oocytes

ABSTRACT

The purpose of this study was to evaluated the effect of beta-mercaptoethanol on resumption of meiosis, in vitro maturation of immature mouse oocytes and resulting embryo development with and without BSO [DL-Buthionine sulfoximine] Material and Germinal vesicle [GV] were recovered from 6-8 weeks old NMRI ovaries and cultured in maturation medium in MEMalpha supplemented with 7.5IU/ml hCG, 100mIU/ml rhFSH, 5% FCS [control group] and adding 100 micro m beta-mercaptoethanol [group 1] or with 5mM BSO + 100 micro m beta-mercaptoethanol [group 2] for 24h. The matured oocytes then were fertilized and cultured for 5 days. Fertilization and development were accomplished in T6 medium.The percentage of GV oocytes reaching to metaphase I [or undergo GVBD] were 78.5%, 85%, 86% in control group, group 1 and group 2 respectively, that no significant difference was detected between groups. The proportion of oocytes that progressed to the metaphase II [MII] stage was minimum within 5mM BSO group [group 2] and maximum within beta-mercaptoetanol group [group 1] with significant difference comparing with control and each other [P<=0.05]. The percentage of embryos reaching to morula stage within beta-mercaptoetanol group was significantly higher than the control group [5% and 12.2% respectively]. None of oocytes treated with BSO could pass the 8 cell stage. beta-mercaptoetanol enhances IVM and improves embryo development. While adding BSO into the maturation medium even with beta-mercaptoetanol decreases maturation and declines the embryo development