Review of enucleation methods and procedures used in animal cloning: State of the art

Enucleation of a recipient oocyte is a crucially important process for nuclear transfer efficiency. Several procedures have been developed and used in the production of nuclear transfer embryos. Although the use of excitable fluorochromes and ultraviolet (UV) light are commonly used for complete enucleation, they also pose the risk of damaging the maternal cytoplast. Telophase and chemically assisted enucleation have also been used for cloning, but the quality and quantity of the recipient cytoplasm varies with the procedure used. This paper reviews various methods used for enucleation, and discusses their benefits and limitations with respect to cloning efficiency.