Scientists at Cornell University may be closing in on the long-sought “holy grail” of male contraception: a safe, reversible, nonhormonal method that completely halts sperm production. In a breakthrough mouse study, researchers used a compound called JQ1 to temporarily shut down meiosis—the critical process that produces sperm—without causing lasting harm. After treatment stopped, sperm production bounced back, fertility returned, and the animals produced healthy offspring.
I think the idea is that this particular drug isn’t suitable as birth control, but having identified that this mechanism/biological pathway can work for birth control, they can look for a less toxic compound to achieve the same effect.