I am presuming by "prosthetic pair" you mean like neuticles that are sometimes put in a castrated dog's scrotum to give the appearance that the dog is intact. They are for appearance sake and don't actually work do they?

Although I expect that this could be done. In this day and age when major organs are transplanted (kidney, liver, heart, etc.) it would seem that testicles could be transplanted from a donor cadaver to a man who had lost his to injury or disease. Should he sire children, this raises all kinds of ethical questions to biggest of which is are they his or the donor's.

Sure! See my PM.