Chromosomes in Primary and Transplanted Leukemias of AKR Mice

Abstract

Chromosome analyses were performed on leukemias of strain AKR mice, mostly on spleen but also on thymus, lymph nodes, and lymphosareomas. Spontaneous primary leukemias in a comparable stage of development showed a varying proportion of cells with aneuploid chromosome numbers, with a usual range from 39 to 42, but also there were cells with 43 and 44 chromosomes in 4 animals. Most of the 17 mice with primary leukemias, and 10 with leukemias and tumors resulting from transplantations, had a modal chromosome number of 40 (diploid). In 5 animals with primary leukemias the mode was 41, and 1 had 2 modes, 42 and 43. More than 80 percent diploid cells were found in 7 mice with primary leukemias and in 6 with leukemias or tumors resulting from transplantations. The chromosome morphology of the diploid cells was generally normal, though in 2 animals with predominantly diploid leukemias, several cells (8 and 18%) had a small marker chromosome. The predominance of diploidy was maintained during continued transplantation. This demonstrates that neoplastic cells can have a diploid chromosome complement without detectable abnormalities.