These results mark a significant advance in research. Scientists have created eggs for the first time using the cells of male mice. They obtained seven pups from two fathers, according to a study published Wednesday and described as "revolutionary" by a researcher.
The study, published in the journal Nature, is the result of research conducted by a Japanese team of developmental biologist Katsuhiko Hayashi of Kyushu University. The team had already found a way to turn skin cells from a female mouse into an egg that could be used to give birth to healthy mice.
A transformation of cells
This time, she tried the same experiment using a male mouse, taking skin cells from its tail, before turning them into so-called pluripotent stem cells. That is, able to transform into any type of cells.
As in humans, male mouse cells have pairs of XY chromosomes, and those of females have XX pairs. During the process, the researchers obtained about 6% of cells losing the Y chromosome that gives them the masculine character, and then duplicated the remaining X chromosome, to obtain the XX pair, specific to the female subject. The transformed cells were used to create eggs, fertilized with sperm from male mice, and then implanted into the uterus of female carrier mice.
A very low success rate
Seven mice were created, out of a total of 630 trials, resulting in a success rate of less than 1%. The mice are healthy and fertile. The technique tested is still far from being used in humans, due, among other things, to a very low success rate and many ethical questions. But this breakthrough suggests reproductive implications, with the possibility for male couples or even a single man to have a biological child without the help of a female egg.
Theoretically, the technique would allow a couple of two men to have a child, with one providing the sperm and the other the egg, according to Dr. Gonen. A single man could even provide sperm and egg, which he says would amount to "a bit of cloning, like that of Dolly the sheep", the first mammal cloned from an adult cell in 1996.
The technique could be used to save an endangered species that would have only one breeding male. For his part, Nitzan Gonen considers the procedure "very ineffective", with 99% of embryos not surviving. It would be all the more problematic in humans, where the gestation time of nine months, compared to only three weeks in mice, would multiply the risk of failure.
Beyond the technical questions, there are ethical questions. "Just because you can do something doesn't necessarily mean you have to do it especially when you're talking about a kind of human being," the Israeli researcher commented.