INVITRO CULTURE OF PIG EMBRYOS

Culture of pig embryos obtained prior to the four-cell stage has been difficult to accomplish. The 'in vitro developmental block' at the four-cell stage can be overcome by a number of methods to allow complete development of pig embryos from the one-cell stage to the blastocyst stage in vitro. Mouse oviducts in organ culture have been shown to provide a suitable environment for pig embryo development. Co-culture of pig embryos with oviductal cells or supplementation of culture medium with pig oviductal fluid results in improved embryonic development in vitro. Modifications to simple culture media have demonstrated that glutamine can serve as the sole exogenous energy source for development from the zygote to the blastocyst stage in vitro. Glucose was not inhibitory to the development of pig embryos in vitro. Addition of taurine and hypotaurine to the medium further increased the degree of embryo development in vitro. A number of different media have been reported that support pig embryo development in vitro. Although the nature of the 'in vitro developmental block' is not known, a number of methods now exist to circumvent this problem in the pig.