From Scientific American:

Mammals, of course, have always reproduced via the sperm of one animal combining with the egg cell of another. But the new research started instead with a skin cell from a mouse’s tail and transformed it into egg cells, then matured those eggs in a laboratory dish and finally fertilized them and implanted them into a female mouse.

Although only 1 percent of the cells led to live births, the animals that were born alive were healthy, fertile, and lived a normal lifespan, says Katsuhiko Hayashi, a stem cell biologist at Kyushu University in Fukuoka, Japan, and the senior author of a paper on the research, published Monday in Nature.

Although this process likely remains decades away from a stage at which it could work in people, the research suggests it may someday be possible for women who lack eggs, or for men without sperm, to get replacement cells made from their own skin. If that becomes possible it could extend the age of human fertility by decades, help preserve endangered animal species and someday perhaps allow same-sex couples to have their own genetic children.

In the meantime, several experts say they are highly impressed by the new study. “This is quite an amazing piece of research,” says Azim Surani at the Gurdon Institute in Cambridge, UK. He was not involved in the latest work, but he supervised Hayashi’s postdoctoral fellowship there. “People might have thought this was science fiction, but it does work,” Surani adds.

In an earlier study published in Cell, Hayashi and his colleagues had shown that they could generate healthy mouse pups by maturing skin-cell-derived eggs inside the mouse mother. In the new work the maturation took place entirely in a lab dish, making it much closer to a process that could one day be used …

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