Chromosomal changes associated with urethan leukemogenesis in mice.

Abstract

AbstractNormal, preleukemic and leukemic thymuses of CTM, C3Hf, C57BL and SWR mice were examined for their chromosome constitution. In untreated infant and young adult animals deviation from diploidy was rare. During and shortly after a brief course of a highly leukemogenic urethan treatment, little variation in chromosome number was found but diploid metaphases had many different chromosome aberrations which became rare a week after completion of treatment. No deviation from normal was observed in thymuses examined 5 and 11 weeks after urethan. The total analysis of 77 thymic lymphosarcomas showed a 40–41 bimodal distribution, although 7 cases had 80% or more diploid metaphases and 3 had 80% or more metaphases with 41 chromosomes. The additional chromosome was always identical or similar to those of the smallest pair.