Photomicroscopy of toxic and non-toxic macrophage phagocytosis. As an example of phagocytosis and degradation by macrophages, Zymosan A was added to living cultures of macrophages and uptake, degradation and regurgitation by macrophage is shown at 2 (a), 4 (b), 8 (c) and 24 (d) hrs. DNA morphology of cells (blue) is normal in all these panels and reveals cells to be in either interphase or mitosis and cell numbers per field remains the same. At 24 hrs, degradation of particles of Zymosan A can be seen as regurgitated debris in the field. In contrast, when macrophages are treated with SWCNT (green; panels E-L) at low (10 μg/mL) and high (100 μg/mL) doses, the nanomaterial is seen to accumulate in the cytoplasm of the cells. At high doses of SWCNTs at 24 hrs (panel L), considerable loss of cell numbers from the surface is observed.