(a) A PMN in patient no. 1 after 1 week of ATRA treatment. Lobulated nuclei with a nuclear bleb (arrow) is seen. rERs are still dilated. Note that the primary granules have become normal in both size and shape and that neither Auer rods nor irregularly shaped inclusion bodies are seen in this cell. (Original magnification × 16,900.) (b) Higher magnification of the cytoplasm of another cell in patient no. 1, showing a structure in which a spherical primary granule (arrow) and an Auer rod are coupled. (Original magnification × 40,000.)