Mammalian cloning: Advances and limitations

For many years, researchers cloning mammals experienced little success, but recent advances have led to the successful cloning of several mammalian sp ecies. However, cloning by the transfer of nuclei from adult cells is still a hit-and-miss procedure, and it is not clear what technical and biologica l factors underlie this. Our understanding of the molecular basis of reprog ramming remains extremely limited and affects experimental approaches towar ds increasing the success rate of cloning. Given the future practical benef its that cion ng can offer, the time has come to address what should be don e to resolve this problem.