The researchers took skin cells from the tails of male mice and converted them into "induced pluripotent stem cells," which have the ability to develop into many different types of cells or tissues.
Next, by growing and treating the male stem cells with a drug, they were turned into female cells and produced functional egg cells.
Those eggs were fertilized, and the scientists implanted the embryos into female mice.
https://www.foxnews.com/science/scientists-create-mice-cells-2-males-first-time