Work

Our immune system protects us against attacks by microorganisms and rejects foreign tissue. Part of our immunity has a hereditary basis, but part of it is acquired and is not present in the fetus. After Macfarlane Burnet theorized that the ability to distinguish between one’s own and foreign tissue is acquired during the fetus stage, Peter Medawar successfully transplanted tissue between mouse fetuses without rejection in 1951. He could perform new transplants on the mice when they became adults, something that did not work when the transplants were not performed during the fetus stage. The results had significance for organ transplants.