A23187-treated HL-60 cells display progressive acquisition of dendritic processes. HL-60 cells (1 × 106) were cultured in a final volume of 2 mL with or without an optimal dose of A23187 (180 ng/mL) for up to 96 hours. Cells were harvested at 24 or 96 hours, resuspended in fresh medium, transferred to polylysine-coated glass chamber slides, and incubated an additional 20 minutes at 37°C. Cells were either immediately examined microscopically (600×) and photographed using DIC (Nomarski) optics (A, B, and C), or were fixed in 100% ethanol, stained in Wright’s solution, and then photographed (D and E). Photomicrographs A, B, and C were taken at consecutive 30-second intervals and depict living HL-60 cells treated with A23187 for 20 hours. Note motility of dendritic processes. Photomicrographs D and E depict fixed, stained, HL-60 cells previously left untreated (D) or treated with ionophore for 96 hours (E).
