Fig. 3

Myeloperoxidase immunostaining of lung sections at 1 month exposure: (a) distilled water as a negative control, (b) 1 mg TiO₂ (Rutile)-exposed lung, (c) 1 mg ZnO-exposed lung, (d) 1 mg NiO-exposed lung, (e) 1 mg CeO₂-exposed lung, (f) 0.6 mg MWCNT (L)-exposed lung. Positive areas were observed mainly at the gathering sites of inflammatory cells at 1 month in NiO-, CeO₂- and MWCNT (L)- exposed groups, and no positive areas were observed in negative control, TiO₂ (Rutile) and ZnO- exposed groups