Incidence and progress of rejection of embryonic limb bud transplants in the turtle, Chelydra serpentina

Abstract Allografts of embryonic limb buds were grafted orthotopically on embryos of Chelydra serpentina . Donors were from a different geographic area, the same geographic area, or siblings. The initial indication of rejection was excessive sloughing of epidermis. This was followed by loss of muscle, claws and bone. Early histological changes involved an infiltration of mononuclear or rejection cells primarily associated with small blood vessels of the connective tissue. Subsequently, muscle and bone were lost and they were replaced by connective tissue. Epidermis and nerves persisted. The skeletal cartilages were isolated from immunological activity. Although the incidence of rejection was essentially the same in sibling and non‐sibling combinations, the initial external signs of rejection occurred earliest when donor and host were from different geographic areas but not later than two years after hatching. The first signs of rejection in sibling allografts occurred not later than three years after hatching. Animals that survived these periods without rejection did not show subsequent rejection.