Rhesus monkeys produced by nuclear transfer.

Genetically identical nonhuman primates can provide a powerful animal model for gene therapy and research activities where the physiological parameters directly or indirectly under study are heritable. Here we demonstrate that nuclear transfer is a viable technology for the production of identical rhesus macaques. Oocytes recovered from gonadotropin-treated females were enucleated by aspiration of the first polar body and underlying ooplasm, then activated by cycloheximide exposure. Individual diploid blastomeres, recovered from in vitro-fertilization-produced embryos (either fresh or frozen-thawed) and used as nuclear donors, were injected under the zona pellucida of enucleated (chromosome-free) oocytes and fused by electric pulses. The reconstituted embryos were cocultured on buffalo rat liver cells before cryostorage and transfer to synchronized host mothers. Of the 9 females receiving a total of 29 reconstituted embryos, 3 became pregnant, with two live births resulting, one male and one female. The parentage of both infants was established unequivocally by genotype analysis at 7 highly variable short tandem repeat loci.