Scientists have successfully grown penises in a laboratory, hoping the organs can be tested on humans within five years.
It is hoped that the new organs, if tested successfully, would be used to help men who have suffered a serious injury in the area, had surgery for cancer or have a congenital abnormality.
The penises, which have been created at the Wake Forest Institute for Regenerative Medicine in North Carolina, are now being assessed for safety, function and durability.
The study is being funded by the US Armed Forces Institute of Regenerative Medicine, with the hope that soldiers with battlefield injuries can be helped.
To avoid the body rejecting the lab-grown organ, the penises would be made using cells from each individual patient's body.
The penises have been developed by the same team of researchers who had successfully grown vaginas in a laboratory and implanted them into four teenage patients. It is hoped that the success from this trial will be used in patients being treated for vaginal cancer or injuries.
