A few years ago, I read a study that sort of concluded that use of steroids PROLONGED the life and number of leydig cells. How? I "think" (I'm an old geezer, so my recollection capabilities these days are lacking!) the study alluded to the theory that the leydig cell has a limited amount of life due to the amount of work it did. So, by suppressing the natural testosterone production with exogenous steroids, the leydig cell takes a break...to come back from vacation when off cycle (provided proper restarting protocols were used). The study used rats as subjects, and somehow determined that the rats that juiced had more leydig cell activity later in life than those that did not.
I know: don't just post this and not provide a link. My bad; sorry, can't find it at the moment.
Anyone else recall a study like this?