Abstract
Simultaneous flow cytometric DNA and volume analysis of normal rat bone marrow cells shows three populations of nucleated cells with different mean volume. Each of these populations proliferates in a distinct cell cycle (alpha, beta, gamma). Normally the alpha-cell cycle has the highest amplitude, the beta-cell cycle is intermediate, and the gamma-cell cycle is low. The alpha-cell cycle was very significantly depressed and the beta + gamma-cell cycle was increased in three different rat leukemias (L5222, Shay, BNML), growing on three different rat strains (BDIX, Holtzmann, Brown Norway). The two parameter analysis further revealed that cells of the beta + gamma-cell cycle were slightly hyperdiploid and hypertetraploid in leukemic animals. The decrease of the alpha-cell cycle and the hyperploidies were more sensitive indicators for the abnormal proliferation pattern than the analysis of one parameter DNA distributions which remained within normal limits in all three leukemias.