In mice, female germ cells can develop into viable ova in male testes, Japanese researchers report this week. Their paper in
"[Our] paper indicated that once the direction of the sex is determined in germ cells, the following influence from the environment seems not to be significant," coauthor Masaru Okabe told
Okabe, from Osaka University's Genomic Information Research Center, and colleagues combined male embryos with female embryos minus the zona pellucida in vitro to create XX-XY chimeric embryos.
Growing the embryos to term, researchers found that the seminiferous tubules of 3-week-old male mice produced meiotic XX germ cells with a normal zona pellucida structure that could fuse with...