Effect of transportation methods on preimplantation development and pregnacy rate of cloned bovine embryos

Abstract

Bovine cloning is promising in basic research, reproductive cloning, and therapeutic cloning; however, the success rate remains low. To overcome this, improving laboratory techniques and applying epigenetic modifiers have been investigated in cloned bovine embryos. In addition, embryo transportation has been considered that can affect embryo survival and quality. Although the transportation materials, namely plastic straw and microtube, were studied in many species, there are few reports about cloned bovine embryos, and no paper compares the efficiency of different transportation systems. Here we investigated the effect of transportation method and transportation materials on preimplantation development and pregnancy rate of cloned bovine embryos. Briefly, each cloned bovine morula was stored in a plastic straw or a microtube without hole or with two holes on its lid for two or four hours in the mini-incubator and then continue to culture in 5% CO2 incubator until blastocyst formation. The results showed that cloned bovine embryos in microtubes with two holes maintained the high rate of hatching blastocysts and high average cell numbers after two- and four-hour incubation in the transportable mini-incubator. Furthermore, the pregnancy rate was higher for cloned bovine embryos stored in microtubes with two holes than the plastic straws’ after embryo transfer. In conclusion, transporting cloned bovine embryos in microtube with two holes could enhance the preimplantation development and pregnancy rate after embryo transfer.