Nuclear Transfer Technologies

Since the advent of Dolly the Sheep in the 1990s, nuclear transfer or cloning technology has been used extensively to examine the developmental potency of embryonic and somatic cell nuclei. The development of nuclear transfer techniques in mammals has been delayed due to the lack of sufficient techniques and knowledge to manipulate mammalian oocytes, zygotes, and embryos. Because the earlier studies on nuclear transfer in mammals were performed without enucleation of recipient eggs, nuclear transferred eggs did not develop well. As early obstacles, sometimes controversial, were overcome, nuclear transfer technologies have found their place in the genetic engineering of a host of animal species. The pronuclear transplantation technique has been applied to clarify the reason for the developmental failure of mammalian parthenogenetic embryos, and it has demonstrated that both female and male genomes have different roles in normal development to term. Current techniques and instrumentation are outlined in detail.