Neutrophil with lipid body. Specialized ultrastructural procedures were used to image this peripheral blood neutrophil. A reduced osmium postfixation step renders nuclear lobes (N) and secretory granules poorly electron-dense but each individual particle of cytoplasmic glycogen is electron-dense, and the single, large, round, membrane-free lipid body (arrowhead) is highly electron-dense. Exposure to cationized ferritin after fixation has provided a uniform layer of electron-dense ferritin particles bound to the plasma membrane. Original magnification × 8,000. (Courtesy of Ann M. Dvorak, MD, Department of Pathology, Beth Israel Hospital, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215.)