A pair of Brazilian conjoined twins who share multiple organs are to undergo a complex separation which will leave them with only one leg each.
Heitor and Artur, who celebrated their fifth birthday in April, are joined at the pelvis and abdomen. They are due to be operated on within a few months.
The twins, from Brazil's Bahia province, share intestines, kidneys and liver, which makes the separation a particularly complicated procedure.
At the moment, Heitor and Artur manage to get around on three legs between them. However, when they are separated, doctors plan to use a leg for the major skin grafts the brothers will need, meaning they will be left with one leg each.
Another serious consideration for the family is that the twins only have one set of genitals, which will mean one of the boys will face a series of reconstructive surgeries in the the future.
However, mum Eliane insists that the pair are aware of the seriousness of the decision and are fully committed to being separated."When I talk to them about the big surgery, they say they want to be separated. It's not just mine and my family's will, it's theirs too.
"They want to be independent. They want to make their own decisions about where to go."
Despite being constantly together from birth, Eliane says that Artur and Heitor are mentally very separate people.
"Each of them has a distinct personality - one is more tough and the other a little sweeter. They are both lovely though."
Eliane, who, like the boys' father, is a teacher, says that being conjoined has forced the boys to learn to get along despite their different personalities.
"Sometimes one is really energetic and awake and the other one is sleeping. But they don't bother each other," she explains. "One never wakes the other up, they let each other sleep.
"Sometimes they want to play at different things, or go to a different place, and we have to try and make them understand that they have to compromise."
In April, the twins underwent a procedure to stretch their skin in preparation for the final operation. Silicon pads were placed under their skin and inflated, in a process compared by Dr Calil to a developing pregnancy. This extra skin will cover the areas exposed by the surgery.
The twins' doctor, Zacharias Calil, who has already performed nine separations of conjoined twins, emphasised that the period after the operation was likely to be the most difficult due to the lack of historical precedent for such a complex separation.
"What makes this very complicated, apart from the separation, is the post-op... We don't know how they're going to react, in terms of their metabolism. There are no studies about that."