A pig kidney transplant has been performed on a human body at a hospital in New York City, USA.
According to US media reports, a brain-dead person was tested for three days and his performance was assessed.
In the medical world, this type of surgery is called Zeno transplantation, in which the organs or tissues of one type of organism are transferred to another type of organism.
Dori Saggio, a professor at Johns Hopkins University in the United States, called the surgery a great achievement.
A conservative estimate is that 17 people die every day in the United States simply because they wait for a human organ transplant.
Medical experts say that despite this successful surgery, there are many obstacles other than approval from the regulator.