胚胎移植时机对牛体细胞克隆胚胎妊娠率的影响

以活体取卵OUP来源的牛卵母细胞为受体胞质，以Holstein奶牛的牛耳成纤维细胞作为供核细胞进行体细胞克隆．并将发育7d的克隆囊胚和体内胚分别及体外胚进行移植，观察移植时机对受孕率的影响。依据代孕牛排卵后天数的不同分为3个实验组，组1：排卵后5-6d（不含6d）；组2：排卵后6—7d；组3：排卵后7～8d（不含7d）。结果显示：对于体外胚胎而言，第2组的受孕率高于第1组（P〉0．05），第3组的受孕率最低（Pt0．05），且120d的受孕率为0。与此相反，对于体内胚胎。第3组的受孕率高于其他2组。通过实验可以证明对于7d的体外胚胎选择在代孕牛排卵后6—7d移植可以得到较高的受孕率：而对于体内胚胎而言则应选择在受体牛排卵后7—8d移植，可得到较高的妊娠率。

Effect of Implantation Time on the Pregnancy of Bovine Somatic Nuclear Transfer Embryos

In the present study, oocytes recovered by ovum pick up （OPU） were used as recipient cytoplasm and Holstein fibroblasts as donor cells for cloning. 7-day-blastocysts from in vivo, in vitro fertility （1VF） and somatic cell nuclear transfer （SCNT）, were im- planted to the surrogates on the 5-6th day （not including the 6th day, group 1）,the 6-7th day （group 2）, and the 7-8th day （not in- cluding the 7th day, group 3） after ovulating respectively. The results showed that blastocysts derived from IVF and SCNT resulted in better pregnancy on 90 d and 120 d in group 2 than that of group 1 （P〉0.05）, arid the lowest pregnancy was observed in group 3 compared with the others （P〈0.05）, while the group 3 was found to be the best one among these groups to the in vivo blastocyst im- plantation. In conclusion, 7 day in vitro embryos should be implanted to the surrogates on the 6-7th day after ovulation while 7day in vivo embryos should be implanted to the surrogate on the 7-8th day after ovulation.