To Derrick Smith concerning his cryptorchid ferret: Derrick: Retained testicles do not produce sperm. The heat of the body cavity is too much for spermatogenesis. That is why, in most species, LGod has put them OUTSIDE of the body cavity. We know that one retained testicle will never produce sperm, but can produce all of the hormones which bring a male into season, unfortunately. Regarding the other testicle - depending how long it stayed inside the body cavity, there may have been enough permanent damage that it, too will not produce sperm, or produce at such a low levels that conception will not take place. What retained testicles WILL do, however, is produce tumros. The incidenceof tumors is FAR higher in retained testicles. I have seen two, three, up to FOUR different types of tumors, all in the same retained testicles. While the chance of metastasis is low, when they do become malignant, they spread rapidly. My advice - go with your original plan - NEUTER. Bruce Williams, DVM Department of Veterinary Pathology [log in to unmask] Armed Forces Institute of Pathology (202) 782-2600/2602 Washington, D.C. 20306-6000 [Posted in FML issue 1069]