Genetics Female clones of a male mouse A gene-editing tool can reliably turn male mouse embryos into healthy females – a feat that could be valuable for conservation, finds Chris Simms MALE mouse embryos have been turned into females by a procedure that involves eliminating the Y chromosome. The technique relies on CRISPR gene editing and has been used to create healthy and fertile female and male mice, both of which are clones of the father. the Y chromosome from male mouse embryos. of himself, which is like sci-fi.” Novak agrees the technique may be useful for frozen tissue samples from endangered or extinct species, where we have samples from only one or two individuals. …