Generation of chimeras by fusion of preimplantation embryos of two species. There is no known case of such a chimera including a human embryo. Therefore, it is described using an example of two other mammalian species. However, it is quite likely that, e.g., a chimpanzee/human chimera, produced in the same way would be viable. Fehilly, C.B. et al. (1984) Interspecific chimerism between sheep and goat. Nature 307, pp.634-636 Live-born and fully viable sheep-goat chimeras were produced by fusion of one 8- cell sheep embryo with three 8-cell goat embryos and transfer of this combined embryo into a goat uterus.