Electron micrographs of bone marrow from patient 2 before granulocyte colony-stimulating factor treatment.

(A) Low magnification of the bone marrow shows degenerating cells (*), few mature neutrophils (**), and promyelocytes (arrows). Neutrophils with convoluted nuclei (arrowheads), a sign of early apoptosis, are observed. Magnification ×4000. (B) Macrophage in the bone marrow contains several phagosomes (arrows) with cellular debris of neutrophils. Neutrophil (arrowheads) with a distinguishable nucleus (*) and granules is discernible in 1 of the phagosomes. N, macrophage nucleus. Magnification ×6500. (C) Neutrophil in an early stage of apoptosis. The nucleus is convoluted (arrowheads), and the chromatin is condensed and distinctly circumscribed, forming dense granular masses (*) along the inner surface of the nuclear envelope. Magnification ×7500. (D) Neutrophil in a later stage of apoptosis. The cell shows cytoplasmic blebbing (arrowheads) and cellular fragmentation (arrow). N, nucleus. Magnification ×13,000. (E) Promyelocytes observed in the bone marrow. The cell at the bottom left appears normal and has a large, round nucleus (N), numerous granules, and a well-developed rough endoplasmic reticulum (arrows). The cell at the top right is apoptotic, as indicated by the fragmented nucleus (*), and has distinct areas of condensed chromatin (arrowheads). Magnification ×5500.