A xenograft is a transplantation between which categories?

• A. Within the same individual
• B. Between individuals of the same species
• C. Between different species
• D. Between identical twins

Answer: (C)

Xenograft means a transplant between different species. The word xeno- signals foreign, so the donor and recipient come from distinct species, not just different individuals of the same species. This is different from autografts (within the same animal) and from isografts or allografts (between individuals of the same species, with isografts being genetically identical or nearly identical pairs, like identical twins or inbred strains). In research, a human tissue graft into a mouse is a classic xenograft, illustrating the cross-species nature. Because the immune system sees the donor tissue as foreign across multiple species differences, xenografts face strong rejection and often require immunosuppression or immunodeficient hosts.