The common understanding is that reproduction typically requires the involvement of two sexes. However, a group of scientists in Japan may have recently challenged this assumption.
A team led by Katsuhiko Hayashi, an Osaka University professor of genome biology, has successfully produced mice with two biological male parents.
This achievement represents a significant milestone in the field of reproductive biology, and was the result of years of painstaking and rigorous laboratory research.
The scientists initiated their work with skin cells obtained from the tails of two adult male mice that had been cultivated in a laboratory. Comparable to male humans, these cells carried one X and one Y chromosome.
Subsequently, the team reprogrammed these cells into induced pluripotent stem cells (iPSCs), which had previously been converted by scientists into an embryonic state. During the culture of these iPSCs, some of them spontaneously shed their Y chromosome, resulting in the creation of 'XO' cells.
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Upon examining the cultured 'XO' cells, the researchers discovered that some of them had acquired two X chromosomes due to mistakes in cell division. Consequently, these cells exhibited female chromosomes despite having been derived from male cells.
Upon examining the cultured 'XO' cells, the researchers discovered that some of them had acquired two X chromosomes due to mistakes in cell division. Consequently, these cells exhibited female chromosomes despite having been derived from male cells.
The research team transformed the XX cells into precursors of eggs and sperm, and stimulated them with the necessary signals to develop into egg cells. After being fertilized with sperm and implanted into a mouse uterus, these eggs resulted in the birth of several newborn mouse pups.
Hayashi pointed out that out of 630 mouse embryos implanted, only seven produced living offspring. However, the low success rate was not attributed to the sex chromosome conversion. Instead, he clarified that it was mainly due to the fact that cells cultured in a laboratory are usually less robust than those found in a living organism.
While the research is still in its preliminary stages, it holds potential for the possibility of same-sex couples producing offspring with genetic contributions from both parents.
The professor clarified in an interview with CNN that: "It (will be) difficult to produce babies from male-male (human) couples because of both technical and ethical reasons. But it is theoretically possible to produce babies from male-male couples, as shown in this study."
Nonetheless, Hayashi acknowledged that producing sperm from female cells is more difficult since they lack the crucial Y chromosome.
According to Mike McGrew, who holds a Personal Chair in Avian Reproductive Technologies at The Roslin Institute of the University of Edinburgh, this method holds promise for aiding in the conservation of endangered species.
McGrew stated that it is presently unclear whether other mammalian species would undergo the same spontaneous Y chromosome loss and X chromosome duplication. Nevertheless, he regarded the results as a 'tremendously exciting discovery for the preservation of species.'
