Acceptance of Tumour Homografts by Thymectomized Mice

Abstract

RECENT experiments in guinea pigs¹, rabbits² and mice^3,4 indicate that the thymus plays an important part in the development of immunological competence. Although the observations that patients with acquired agammaglobulinæmia often have a benign thymoma^5,6 suggested a role for the thymus in immunological reactivity it was only very recent investigations which led to consideration of the thymus in immunological development. Glick et al.⁷ and Mueller et al.^8,9 showed that removal of the bursa of Fabricius, a lymphoid organ developing as an outpouching of the posterior gut and an organ homologous to the thymus in several ways, interfered with the ultimate development of full immunological competence. Mueller et al.⁹ showed further that prevention of development of this lymphoid organ by treatment of chick embryos with progestational hormones, for example, 19-nortestosterone, provided potent inhibition of the development of immunological capacity.