As long as you don't need a microscope to see it.

Lab-grown penises could be tested on men within the next five years after successful experiments on rabbits.

North Carolina's Wake Forest Institute for Regenerative Medicine researchers are hoping to get the go-ahead from the U.S. Food and Drug Administration after "encouraging" results from their work with rabbits since 2008, the Guardian.com reports.

"The rabbit studies were very encouraging," institute director Prof. Anthony Atala is quoted by the Guardian, "but to get approval for humans we need all the safety and quality assurance data, we need to show that the materials aren't toxic, and we have to spell out the manufacturing process, step by step."

The penises would help men who have had cancer surgery or suffered severe injuries and would be grown from the patient's own cells.

Because of that, the procedure is not suitable for sex-change operations.