A Japanese biologist, Katsuhiko Hayashi, has managed to create both sperm and egg cells from stem cells in mice. Not only that, but Hayashi was even able to produce a viable baby mouse using these same stem cells. His research may have far-reaching consequences for human fertility, one of which would be that two men or two women could make a biological baby together.
Egg and sperm cells come from a type of cell called “germ line cells” early in the stages of embryonic development. The goal of Hayashi’s research was to provide a supply of these germ line cells for other researchers without needing access to costly and sometimes controversial stem cells. Working with a colleague, Mitinori Saitou, he was able to get germ line cells from skin cells in mice. He used these cells to produce sperm and egg cells which were then fertilized and implanted in other mice.
According to Hayashi, the birth of a live baby mouse was just a side effect of his research. Soon after it was published, the birth was noted by people who cannot have biological children of their own, and who hope that his research could eventually be applied to humans. Hayashi, Saitou and their team are now exploring this possibility but they caution that humans are far more complex systems than mice.