[Cloning: applications in humans. I. Technical aspects]

The successful cloning experiments in mammals such as the sheep and mouse prompted speculations on clinical application in humans. Cloning is possible by nucleus transplantation and by embryo splitting. Nucleus transplantation does not result in a genetically completely identical individual because the mitochondrial DNA originates from the ovum donor. Embryo splitting may be regarded as the artificial production of a monozygotic multiplet. Possible applications of cloning in humans belong in the context of reproduction (treatment of couples with subfertility, with genetic problems or with a 'replica motive'), transplantation of genetically identical tissue, and scientific research.