Effect of Neonatal Thymectomy on the Immune Response in the Chicken

Abstract

THE function of the mammalian thymus has recently become a matter of considerable interest in the field of immunology. It is now reasonably clear that the presence of the neonatal thymus is essential if the animal is to develop the capacity to reject homografts. This has been shown by Miller¹and by Arnason et al.², who thymectomized mice and rats respectively within 24 h of birth and demonstrated that a skin homograft placed on the animal several weeks later was either permanently accepted¹or showed a prolonged rejection time². This has lent considerable support to the view, originally proposed by Fichtelius³, that the thymus is a primary organ of lymphocytopoiesis which, during the first week of life, sends out lymphoid cells to colonize other lymphoid organs, and where on appropriate antigenic challenge will be stimulated into immunological activity. However, some recent results from Miller⁴have indicated that the influence of the thymus on the development of immunological competence may not be purely cellular, but may be of a hormonal nature.