Morphologic characterization of leukemias. (A) Representative samples of Wright-stained bone marrow preparations, × 100 magnification. Group I, more than 80% blasts: IA, 2 distinct blast populations; IB, myeloblasts with pale granules; IC, myeloblasts with coarse granules. Group II, less than 80% blasts: IIA, 20% or more monocytes and differentiated myeloid cells; IIB, 20% or more differentiated myeloid cells and less than 20% monocytes. (B) Distribution of leukemias within 5 subgroups defined by index cases presented in panel A. Genotypes of leukemias are listed at the top, subgroup number and its major characteristics are listed to the left, and column numbers are listed at the bottom. Different intensities of shading within the subgroups defined by genotype listed on top of table illustrate proportions of mice within each group with the particular characteristics. White cells indicate 0% of recipients; black cells, 100% of recipients.