As promised in the comments section of this recent post, I managed to catch all of my ram lambs this morning to inspect their "masculine equipment." And I have very good news to report:
I was mistaken about Tucker having two testicles with the one being only partially descended! He definitely has two, fully-descended testicles, of equal size. I checked twice and I am absolutely certain about this.
I also inspected Sextant again and I am very certain that he only has one descended testicle.
The wonderful point here is that there is NO indication that the cryptorchid comes from any particular line because there is only this SINGLE instance here on my farm. It does mean that LRO January and S'more Courante produced a cryptorchid/monorchid. But that is the only incriminating fact in the matter. Those two sheep will not be paired again, and I will also carefully monitor all future ram lambs for the same problem and publish any faults I come across in my breeding. It would be easier to not talk about it...simply send cryptorchids to butcher...but no one will learn anything from that. And I would like to think of my efforts as being helpful to the breed as a whole.
The other bit of good news is that my other three ram lambs, Trans Am, Gwilym, and Ian, all have proper equipment. I am so glad of that.