THE USE OF DEOXYCYTIDINE LABELED WITH TRITIUM IN THE 5-POSITION FOR AUTORADIOGRAPHIC STUDY OF LYMPHOCYTES IN VIVO

Abstract
The patterns of labeling of thymic lymphocytes and germinal-center cells of the rat with [5-3H]deoxycytidine (labeled in the 5-position) in vivo were studied by autoradiographic technique, and compared with the patterns of labeling with [G-3H]deoxycytidine (generally labeled). With respect to the thymic lymphocytes, no significant difference was observed in labeling intensity between the 2 labeled markers. In the germinal-center cells, the labeling intensity with [5-3H]-deoxycytidine was significantly weaker than [G-3H]deoxycytidine labeling. The results were discussed in relation to the ability of these cells to utilize deoxycytidine for the synthesis of DNA-thymine, and the pool size of thymidine within the tissue which suppresses such utilization of deoxycytidine by these cells. The thymus contained a large pool of thymidine, while in the lymph node the pool seemed much smaller in size.