ACUTE MYELOBLASTIC-LEUKEMIA IN A COW

A myeloblastic leukaemia was found in a G-year-old Holstein cow. Altho ugh macroscopical lesions were not found in parenchymal organs, the an imal had many neoplastic cells in the peripheral blood, bone marrow, l ymph nodes, and spleen. By light microscopy mosi neoplastic cells appe ared to be agranular blast cells, but some cells contained acidophilic granules and stained positively for naphthol AS-D chloroacetate ester ase and lysozyme. Ultrastructural examination revealed that many of th e blast cells had a few peroxidase-positive granules and corresponded to early promyelocytes. (C) 1996 W.B. Saunders Company Limited