During the infancy days of cardiac transplantation, nonhuman primate hearts were transplanted into humans to save lives. This type of transplantation is best described by which one of the following?

Transplantation from one region of a person to another region of that same person is an autograft and has the best chance of succeeding. When a transplant is done between monozygotic twins, it is an isograft and has a complete MHC compatibility and a good chance of success. Allografts are between members of the same species, and xenografts are between members of different species. Both of these transplants have a high rate of rejection unless immunosuppression accompanies the transplant.