Nuclear transfer for cloning animals

Nuclear transfer (NT), also termed nuclear replacement or nuclear transplantation, is the method of choice for animal cloning. NT is a conceptually simple but technically complex technique. It involves the removing or destroying the nuclear DNA from a recipient cell, and replacing it with nuclear material from an embryonic, germ, or somatic donor cell. The newly introduced DNA interacts with the recipient cytoplasmic environment and, following ill-defined changes in the nuclear DNA, can direct development into adult fertile animals. Compared to other assisted reproductive technologies, the NT process is relatively inefficient. Nonetheless, NT is an important procedure as it allows the study of fundamental questions on epigenetic ‘‘reprogramming.’’ As a practical tool, NT can be used for agricultural and medical applications, especially when combined with transgenic and pluripotent stem cell technologies.