Researchers create fertile female mouse clones by deleting the Y chromosome

Using a CRISPR technique named Y-CUT, researchers eliminated the Y chromosome from cloned male mouse embryos, resulting in XO female mice that were both viable and fertile. The process involved somatic cell nuclear transfer to create the clones, followed by implantation into surrogate mothers. The resulting females carried the exact genetic material of the original male donor, minus the Y chromosome, and were able to mate with male clones to produce normal XX or XY offspring.

Scientists see potential for this method to help rescue critically endangered species that have very few remaining individuals by creating breeding pairs from a single male. However, the approach may be limited because many mammals cannot reproduce with an XO chromosome set, indicating further technical advances would be needed.