Comparison of the ultrastructural properties of HL60 cells treated with DNR alone and in combination with CHX. (A) Transmission electron microscopic overview (left) and detail showing part of nucleus and perinuclear region of control HL60 cell (incubated with vehicle for 5 hours). The inset (arrow; R) shows a polysomal rosette. (B) Cell treated with CHX (3.6 μmol/L) for 4 hours. (C) Cell treated with DNR (8 μmol/L) for 2.5 hours. Note beginning thickening of microvilli, perinuclear accumulation of condensed chromatin and polysomes (inset). (D) Cell treated for 2.5 hours with DNR (8 μmol/L) + CHX (3.6 μmol/L, added 1 hour after DNR). Note budding, separation of nuclear lamina from chromatin (arrows), and dispersal of polysomes (inset). (E) Cell treated with DNR (8 μmol/L) for 5 hours. Note similarity of features with cell in panel D. Panels A-E: scale bar: 5 μm for left subpanels, 0.3 μm for right subpanels, and 0.18 μm for right subpanel insets. The cells in panels A, B, and E are typical for the average cell in the population. The cells in panels C and D are representative of the 10% of cell population with most advanced apoptosis.