Effect of pre-IVF incubation in maturation medium on oocyte maturity,fertilization,embryonic development,and clinical outcomes following embryo transfer

Objective:Collected human cumulus-oocyte complexes(COCs)are usually inseminated after 4 to 6 hours in in vitro fertilization(IVF)laboratories.The purpose of this study was to determine the effect of short-term pre-IVF incubation in culture medium on subsequent oocyte maturation,fertilization,and embryonic development,as well as clinical outcomes.Methods:Sixty patients were divided randomly into 2 groups,pre-IVF incubation for 5 hours:1)with(+)the designed oocyte maturation medium;2)without(-)the designed oocyte maturation medium(transferred directly to fertilization medium for 5 hours before insemination).Oocyte maturation and fertilization were assessed,and the rate of cleavage and good quality embryos were evaluated between the 2 groups on days 2 and 3,respectively.Blastocyst development was based on the remaining number of embryos on day 3,continuously cultured to day 5 after embryo transfer or frozen on day 3,and was compared between the 2 groups.Clinical pregnancy,implantation,and miscarriage rates were also compared.Results:Oocyte maturation rates did not differ between groups(85.8±14.1%vs.90.7±9.1%).However,the range of oocyte maturation rates(58.3%-100.0%)for each patient was significantly higher in the(-)group than in the(+)pre-incubation group(71.4%-100.0%).There were no differences in fertilization rates(89.9±10.0%vs.86.5±12.2%)and good quality embryos(70.8±19.1%vs.62.1±23.7%)between groups;however,the blastocyst development rates were significantly different between groups(73.1±20.1%vs.58.8±18.2%,P<0.05).Nevertheless,clinical pregnancy(62.5%vs.61.1%)and implantation(46.9%vs.47.2%)rates did not differ between groups.Conclusions:These results indicate that a short pre-IVF incubation time in the designed culture medium promotes oocyte maturation and embryonic development,suggesting that short pre-IVF incubation of COCs in the designed culture medium may be important for subsequent final oocyte maturation and early embryonic development.

牛的3种单个早期胚胎中基因表达的差异

为建立哺乳动物单个早期胚胎中基因表达的分析方法,解决胚胎实验中取材困难的矛盾,本研究以牛体内受精胚(invivo cultured,IVC)、体外受精(in vitro fertilization,IVF)和体细胞核移植(somatic cell nuclear transfer,SCNT)3种来源的7日龄囊胚作实验材料,通过单个胚胎直接裂解后进行逆转录结合随机引物指数扩增的方法富集相应cDNA。对克隆囊胚cDNA库中随机挑选的15个阳性克隆进行测序和EST分析。并运用特异性的引物,对哺乳动物胚胎发育的3个重要基因Nanog,Oct-4和Sox2的表达进行了扩增和表达检测。结果表明,在哺乳动物胚胎囊胚阶段,这3个维持细胞多能性的相关基因的表达都相当活跃;相对于体内胚和体外受精胚,克隆胚中这3种基因的表达明显偏低。本方法为牛植入前胚胎发育阶段特异性基因的筛选和基因表达模式的研究提供了有效的材料和技术途径。