A male Pill that provides a safe, effective and reversible method of contraception has been brought a step closer by scientists.
Researchers identified two proteins that can be blocked to prevent the "launch" of sperm cells from the testes during ejaculation.
Knocking out the proteins in genetically engineered mice resulted in male animals that were completely infertile, though they continued to mate normally.
A similar goal could theoretically be achieved by suppressing the proteins with drugs, say the scientists. In fact, medicines for prostate enlargement and high blood pressure already exist that block one of them.
"This concept is indeed a feasible mechanism of producing male contraception," the Australian and British researchers wrote in the journal Proceedings of the National Academy of Sciences.
A male contraceptive pill has been the Holy Grail of fertility scientists, but one that has proved frustratingly elusive.