Clonal propagation of primate offspring by embryo splitting

Primates that are identical in both nuclear and cytoplasmic components have not been produced by current cloning strategies, yet such identicals repre sent the ideal model for investigations of human diseases. Here, geneticall y identical nonhuman embryos were produced as twin and larger sets by separ ation and reaggregation of blastomeres of cleavage-stage embryos. A total o f 368 multiples were created by the splitting of 107 rhesus embryos with fo ur pregnancies established after 13 embryo transfers (31% versus 53% in vit ro fertilization controls). The birth of Tetra, a healthy female cloned fro m a quarter of an embryo, proves that this approach can result in live offs pring.