Effect of the Thymus on Peripheral Lymphoid Organs

Abstract

The term “peripheral lymphoid organs” needs some explanation. As has been described earlier, there is a distinct dichotomy in the response of the different lymphoid organs to antigenic stimulation—the lymph nodes, splenic lymphoid follicles and the Peyer’s patches responding by hyperplasia and increased mitotic activity, but the thymus exhibiting no morphological changes. The blood lymphocytes seem also to be part of the antigen-responsive group of lymphoid organs since their number is influenced by antigenic stimulation and the work of Gowans has clearly shown that (excluding the thymus) lymphocytes recirculate from one lymphoid organ to another via the blood (Gowans and Knight, 1964). It has also been mentioned that many workers feel that the thymus is a central factory producing lymphocytes which are distributed to lymphoid organs around the body.