Figure 4.

Effects of TiO₂NP exposure on inflammatory cell infiltration and mucus production in the lungs. (a) Lung tissue is stained with hematoxylin and eosin (×200), (b) and periodic acid-Schiff stain (×200). VC, PBS intranasal instillation; OVA, OVA challenge + PBS intranasal instillation; TiO₂NPs 5, 10, and 20, OVA challenge +5, 10, and 20 mg/kg of TiO₂NPs intranasal instillation, respectively. Black arrows indicate inflammatory cell infiltration. Black arrowheads indicate mucus within lung epithelial goblet cells. Data are represented as means ± SD, n = 6. ^# p < 0.05, ^## p < 0.01, significantly different from the VC group; * p < 0.05, ** p < 0.01, significantly different from the OVA group. Bar = 50 μm.