Abstract
Banded karyotypes were analyzed in 20 cases of spontaneous leukemias of the AKR mouse, of which 13 showed a mixed-cell population consisted of both diploid (40 chromosomes) and hyperdiploid (41 or 42 chromosomes) cells, while the remaining 7 had exclusively diploid cells. The diploid cells were karyotypically indistinguishable from the normal somatic complement of the mouse even after banding analyses. Most of the hyperdiploid cells in 12 of the 13 cases had 41 chromosomes in which trisomy 15 was the predominant feature. For the remaining minor fraction of aneuploid cells, trisomies for chromosomes 8, 10, 12 and 17, or an extra copy of the X or the Y chromosome were encountered only once for each. Also noted was a case in which the majority of aneuploid cells had two Y chromosomes, though these cells coexisted with the trisomic-15 cells.
