This week in Nature, the New York Stem Cell Foundation Laboratory's Dieter Egli and his colleagues report their "development of human oocytes after genome exchange arrests at late cleavage stages in association with transcriptional abnormalities." The team says that through this process, "if the oocyte genome is not removed and the somatic cell genome is merely added, the resultant triploid cells develop to the blastocyst stage," and adds that "stem cell lines derived from these bla