Development of the techniques for nuclear transfer in pigs.

Nuclear transfer in pigs was developed in the late 1980's. The techniques were based on previous studies in frogs, mice and cattle. Within stage nuclear transfer, pronuclear exchange, was followed by the transfer of nuclei from cleavage stage embryos. While these have resulted in term development, many problems remain. Recently progress on the problem of inadequate oocyte activation has been made and now there can be a refocus on the other aspects of the nuclear transfer procedure. The emphasis in developing the cloning/transgenic technology is easily justified, not so much by the ability to produce genetically identical animals for production agriculture, but for the potential to use a cell line that can be genetically engineered prior to the nuclear transfer. Pigs with specific genetic modifications will have a great impact on production agriculture as well as human medicine.