Many transgender men do not opt for genital reassignment surgery. But for those who do want it, the procedure could be set to change following a new breakthrough.

Scientists have reportedly successfully grown half a dozen human penises in a lab and say they are steadily approaching transplantation in the next few years.

In 2008, urological surgeon Anthony Atala and his colleagues attached a bioengineered penis to 12 male rabbits.

All rabbits attempted to mate (like rabbits), eight had ejaculated and four produced offspring.

With the successful animal trial, the team are now wishing to do the same for humans.

At the moment, the only options available for trans men and men who have lost their penis is either enlarging the clitoris or constructing a penis using tissue from other parts of the body with a penile prosthetic inside.

Atala’s method isn’t growing a penis from a petri dish. He takes a donor penis, soaks it in enzymes that remove the donor cells, and then uses the patient’s cells so there is no adverse reaction.

‘You’re left with a mostly collagen scaffold – a skeleton if you like, that looks and feels just like the organ,’ James Yoo, one of Atala’s collaborators at the institute, told The Guardian.

‘Think of it like a building. If you remove all the furniture and the people, you’re still left with the main structure of the building. Then you replace the tenants with new ones. That’s the whole idea. It’s just that the building is a penis and the tenants are cells.’

By doing this, a man could have a biological functional penis that would be ideally less invasive than the current procedure.

While they haven’t got a date for the first human transplant test, they expect it to happen in five years.

‘In the end we’re aiming for the entire size of the organ,’ says Atala. ‘But in reality our first target is going to be partial replacement of the organ.’

For those who are concerned where these test results originate from, we contacted the British Union for the Abolition of Vivisection – the charity campaigning to end animal experimentation.

Dr Katy Taylor, Head of Science for the BUAV, said: ‘We are shocked to hear that rabbits are being used in this type of research.

‘There are pioneering techniques already being used and it is not necessary, scientifically or ethically to subject rabbits to such cruel experiments.’