CYTOKINETIC STUDY ON ERYTHROID PRECURSORS OF RAT AND MOUSE

Abstract

Cell kinetics of the erythroid precursors was investigated in normal mice and rats by 3H- thymidine labeling method with or without simultaneous administration of colchicine, and the following results were obtained : 1) DNA synthesis time (S-time) of the erythroid precursors assessed by the labeled mitosis method was 7 hours in mice and 7.5 hours in rats, G2- and M-time were 1.5 hours and 1.0 hour, respectively, in both animal species. 2) S-time of basophilic erythroblasts of mice assessed by the 3H-thymidine labeling method with colchicine was 7 hours and that of the polychromatic erythroblasts was 8 hours. In rats, S-time of both basophilic and polychromatic erythroblasts was equally 7 hours. G1-time of basophilic erythroblasts was 2 hours both in rats and mice. Time for remaining in G1-phase of the polychromatic erythroblasts was 6 hours in mice and from 7 to 10 hours in rats. 3) Three percent of the basophilic erythroblasts and 7% of the polychromatic erythroblasts were in non-proliferating fraction in mice during 6-7 hours' observation period. Moreover, labeled mitosis curve of the erythroid precursors was different between mice and rats. In rats, the rate of labeled mitoses of the erythroid precursors increased rapidly and attained to 100% 3 hours after the first administration of 3H-thymidine, while in mice the maximum rate was about 80%. These findings may indicate the difference in erythroblastkinetics between two animal species. From the above results, cytokinetics of erythroid precursors was discussed.