In the study, adult male rabbits with severely damaged penises received a graft of specially engineered penile tissue. The animals then re-grew full penises that functioned normally -- even to the point of successfully impregnating females.

The researchers have been working on this for a long time in a variety of different organs. It's not yet clinically available, but if it works and proves safe and effective, it would be a tremendous advance.

The researchers found that the new penises were similar in structure to natural rabbit penises. The "artificial penis" also achieved and maintained erectile pressures equal to those of normal rabbit penises. A preliminary study involved animals but rabbit tissue is fairly similar to human tissue. If it can be done in rabbits, it probably can be done in humans.

When the test came, the rabbits that had received the new penises were presented with sexually mature females. Things proceeded just as nature intended. Mating activity in the animals with the engineered penis resumed by 1 month after implantation. Presence of sperm was confirmed in the vaginal vault of the female partners, and all females conceived and delivered healthy pups.

If the researchers could re-grow and replace worn-out tissue also in other body parts, that would have tremendous implications.