The researchers found that DNA methylations are erased in female iPS cells but not in male cells. (sciencedaily.com)
Norbert Gleicher, a gynecologist and the chairman of the Center for Human Reproduction in New York City, took 21 human female embryos and added male cells to each one. (discovermagazine.com)
He inserted male cells because the Y chromosome is a genetic marker that can be tracked, making it easy to see where and how the injected cells integrate into the recipient female embryos. (discovermagazine.com)