Suture of blood vessels
Before Carrel's discoveries, circulation could not be established through transplanted tissue. He developed a new surgical technique which allowed blood vessels to be attached to a functioning circulation system. Performing experiments in dogs, cats, rabbits and eventually man, he changed surgical procedure, and made it possible for lost limbs to be re-attached.
He later turned his attention to transplant surgery, and found that although it was possible to remove and reattach organs or limbs from an animal, transplants between animals of the same species led to complications and rejection of the foreign tissue. He noted that different animals accepted the transplanted material with different degrees of success, and hoped that in the future they would discover why. Many of his experiments concerned kidney transplants, and the lifesaving operation which is commonplace today would never have been possible without his work.