Fig. 5

Abnormal microtubule arrangements in cilia cross-sections. Ciliary axoneme abnormalities were tallied in 224 control-treated and 234 MWCNT-treated cross-sections from a single donor. Sections were categorized as normal cilia (represented in panel a), axoneme abnormalities (represented in panel b, arrow points to singlet), or dynein arm abnormalities (not found). While MWCNT treatment increased axoneme abnormalities above control levels by 3-fold (6.0% vs 1.9%), the absolute numbers of abnormal cilia in MWCNT treated cells are not sufficient to alter cilia beating/clearance. Ultrastructural imaging was also used to verify the presence of MWCNTs within the cell 24 h after treatment of undifferentiated cultures. MWCNT fibers are observed in vesicular structures (c) and free in the cytoplasm (d)