Phagocytosis of MWCNT in vivo. After instillation of 2 mg MWCNT, (A) lung and (B) lymph nodes sections were observed by TEM and reveal the presence of MWCNT agglomerates in macrophage vesicles. Quantification of (C) EEA1 mRNA and (D) actin beta mRNA on the lung of rats treated by 1, 10 or 100 μg MWCNT support the MWCNT phagocytosis capacity of macrophages. Results are the mean of ± SD obtained on 6 rats. * Significantly different (p < 0.05) from control group.