Studies on the Lymphocyte Production. Investigations on the Nucleic Acid Turnover in the Lymphoid Organs

Summary. The importance of the various lymphoid organs as a source of blood lymphocytes is studied by determinations of the rate of desoxyribose nucleic acid formation in the organs under examination. The rate of formation of nucleic acid is estimated by means of the radioactive indicator method. The animal material is normal albino rats in different age groups. A large nucleic acid turnover is observed in the lymphoid organs. The greatest renewal takes place in the thymus, the rate of renewal in mature animals being 5–6 per cent during the 3 hours' experimental period. The corresponding figures for the lymph nodes and the spleen are only 1–2 per cent. Various considerations lead to the assumption that the desoxyribose nucleic acid turnover affords an estimate of the lymphocyte production in the different lymphoid organs. According to this conception, calculations show that the thymus must be the most important lymphocytopoietic organ except in old age when the weight of the organ is markedly reduced. Compared with the high thymic activity the other lymphoid organs possess only a slight lymphocytopoietic function.