Reutilization of Thymidine in Various Groups of Rat Bone Marrow Cells

Thymidine reutilization was studied in single cells of the rat bone marrow. Using ³H-TdR in parallel with ¹²⁵I-UdR in conjunction with the autoradiographic technique, cells of the erythrocytic series, the megakaryocytic group, and the lymphoid cells were analyzed. Reutilization of thymidine was observed only in those cells known to synthesize DNA. An estimate of the amounts of the thymidine reutilized by the salvage pathway indicated that approximately 40-60 per cent of the thymidine in the blast cells is supplied from DNA of dead cells. This value is similar to that reported previously for whole bone marrow cell populations, suggesting the presence of a common thymidine pool within the bone marrow.