Abstract
Distribution of chromosome numbers and karotypes were analysed in 26 individual leukemias developing in the mouse strains C3Hf*/Lw, C3Hf*/Gs, C3Hf*/Fg, RFM* and BALB*/c. They developed after natural infection with MLV transmitted to the offspring through mother's milk. Among the examined 26 leukemias, 24 were lymphocytic, while the remaining two were granulocytic. Twenty-three had 40 chromosomes as modal number, all characterized by telocentric centromeres. The remaining three leukemias were remarkable by showing a mode of 41 chromosomes. In leukemias characterized by the modal number of 40, second peaks appeared which differed by the strain. No marked differences in karyotypes were found between granulocytic and lymphocytic leukemias. Lymphocytic leukemias developing after thymectomy showed also similar karyotypes to those developing in intact mice.
Differences in karyotypes in various leukemias induced by virus infection, radiation and chemical treatment, and those developing spontaneously were discussed.
