CLASSIFICATION OF INITIAL LEUKEMIC CHANGES IN RATS FED N,N′‐2,7‐FLUORENYLENEBISACETAMIDE

Leukemia was Induced in rats which were fed N,N′‐2,7‐fluorenyIene‐bisacetamide. This leukemia developed from a solitary lesion to a scattered and further a diffuse lesion. The appearance of orthochromatic erythroblasts In the peripheral blood was utilized for detection of solitary lesions. Almost all bones of the body were examined histologically. The classification of leukemia was performed from diffuse lesions toward scattered and solitary lesions. Solitary lesions were classsifled into mature granulocytic, erythroblastic, mlcromyeloblastic, and unclassified types. No solitary lesion of myeloblasts type was identified. Each type showed its particular histological pattern from the initial stage, though solitary lesions were composed of more Immature cells than those of scattered and diffuse lesions. Mature granulocytic and erythroblastic leukemias are considered to begin as one or a few nodular foci mainly in the bone marrow. Micromyeloblastic leukemia seems to originate in the spleen and bone marrow.