Synthesis of Immunoglobulins by Rat Thymus after Thymic Irradiation

THE thymus distinctively lacks plasma cells and pyroninophilic precursors, even after massive parenteral injection of protein^1–3. Direct injection of antigens into the thymus in guinea-pigs, however, can induce the formation of germinal centres, plasma cells and the production of antibodies⁴. An increase in the plasma cell population has been observed in the spleen, lymph nodes and bone marrow of chimpanzees⁵, rats^6–9 and germ-free mice¹⁰ after whole body irradiation.