Incorporation of Pyrimidine Nucleosides in Lymphoid Tissues of the Mouse Using 5-Fluorodeoxyuridine and [5-3H]Deoxycytidine

Abstract

ABSTRACT. The distribution of cells labeled with generally tritiated deoxycytidine ([G-3H]CdR) was similar to that of cells labeled with 5-tritium labeled deoxycytidine ([5-3H]CdR) in the thymus and mesenteric lymph nodes. In the thymic cortex and germinal centers of mesenteric lymph nodes, however, radioautographic reactions showed more intense labeling with [G-3H] Although mitotic analyses consistently reveal high rates of cell division in the thymic cortex and germinal centers of rats and mice (1,4,5,9,10), the cells in these areas are characterized by weak labeling with tritiated thymidine ([3H]TdR), whereas lymphocytes outside these anatomical regions of the same organs are labeled intensely with the same nucleoside (1, 6-10, 12, 18, 25). Recently, tritiated deoxycytidine ([3H]CdR) or radioiodine-labeled 5-iodo-2'-deoxyuridine has been used as a substitute for [3H]TdR to study lymphocyte production (1,2,12,14,(16)(17)(18)(19)(20)(21)23). Radioautographs revealed that lymphocytes in the thymic cortex and germinal centers were much more heavily labeled with generally tritiated deoxycytidine ([G-3H]CdR) than with [3H]TdR, whereas outside the germinal centers labeling was far more intense * present address: