Q.Write down the observations of Medaver in transplantation technology.

Medawar's experiments established that graft rejection is an adaptive immune response with memory, and that immunological tolerance can be experimentally induced.

Peter Medawar's key observations in transplantation biology:

• Autografts (tissue transplanted within the same individual) and isografts (between genetically identical individuals, e.g., identical twins) are accepted and survive normally.
• Allografts (tissue transplanted between genetically different individuals of the same species) are rejected by the recipient's immune system.
• 'Second-set rejection': when a second skin graft is taken from the SAME donor and transplanted onto a recipient who had already rejected an earlier graft from that donor, the second graft is rejected much faster and more vigorously than the first. This showed that graft rejection involves immunological memory, characteristic of the adaptive immune response. …