| Abstract: | Transmission electron microscopy, scanning electron microscopy, and ultrastructural cytochemistry were utilized to study megakaryoblastic cells from four patients suffering from megakaryoblastic leukemia. The results show that megakaryoblastic leukemic cells have a unique ultrastructural appearance, surface architecture, and cytochemical activity. The cells are positive for platelet peroxidase cytochemical reaction, which is localized in the perinuclear space and endoplastic reticulum, but not in the Golgi apparatus and cytoplasmic granules. They have a rather smooth surface and display blebs or tuberculi which are different from those in other types of leukemic cells as seen under the scanning electron microscope. The megakaryoblastic leukemic cells also show a special appearance under the transmission electron microscope, such as a cytoplasm which contains numerous small mitochondria, mostly concentrated in one pole of the cell. These ultrastructural and cytochemical characteristics of the megakaryoblastic leukemic cells revealed by the combined techniques are very useful in the diagnosis of megakaryoblastic leukemia. |
