The immunological status of ovarian homografts in fowls.

Using material known to be genetically heterogeneous, orthotopic homografts of ovary have been made into twenty-two castrated or partially castrated male fowls. Fifteen of the grafts have survived for long periods (> 280 days) and six have ovulated. No graft, once hormonally active, showed subsequent signs of regression. The presence of testis prejudiced survival and normal development of the grafts, but, within the limits of this material, greater genetic disparity between donor and host did not. Erythrocyte elimination and haemagglutination tests on three birds with successful ovary grafts demonstrated a state of humoral immunity against the ovary donors, but skin grafts from the ovary donors survived indefinitely (> 235 days) in two of the three. It is suggested that ovary grafts survive by a process of `self-enhancement', due to the release of a high ratio of H- to T-antigens, and that this also tends to protect a subsequent skin graft from the same donor.