Cloning of sheep and cow embryos.

The results of experiments aimed at cloning of sheep and cattle embryos are described. Two experimental approaches were used to study the developmental potential of blastomeres from sheep and cow embryos: (i) blastomere separation followed by culture and (ii) fusion of isolated blastomeres with enucleated eggs followed by culture. Both approaches allow embryos to be cloned, but whereas blastomere separation allows only a relatively small number of genetically identical animals to be produced, nuclear transplantation will probably open the way for large-scale cloning of livestock.