Resumen de Only two genes maketh the man... or mouse
Being a male is easier than it looks. The defining genetic feature of maleness, the Y chromosome, contains only two genes that are absolutely essential for fathering offspring--at least in mice. The discovery may one day lead to new infertility treatments for men. When Monica Ward's team used what's called round spermatid injection to insert the immature sperm into eqgs, fertilization was successful about 9% of the time. That's a much lower success rate than the 26% they see with normal, Y-bearing mice. Still, the offspring appeared to develop into healthy, fertile adults.
