Fig. 1
Experimental protocol and representative macroscopic photographs of the lungs of F344 rats after 2-year whole body inhalation exposure to TiO2 NP. A total of 400 F344 rats were used in the experimental protocol (A) for the two-year whole-body inhalation exposure experiment. Representative macroscopic photographs of the lungs immediately after the final dissection are shown for male and female rats in the 0.5 mg/m3 group (B, E), 2 mg/m3 group (C, F), and 8 mg/m3 group (D, G). Bar: 1 cm. For female rats in the 8 mg/m3 exposure group, macroscopic photographs of the rib surface (H) and cardiac surface (I) of the same animal showed the characteristic localization of white clusters. Bar: 1 cm. Enlarged photographs (J, bar: 1 mm) and cross-sectional photographs (L, bar: 1 mm) of white clusters show that they can be distinguished into two characteristic foci: white–gray spots (M, bar: 500 μm) and small pure white spots (K, bar: 100 μm). Figure 1I shows a reversed image. High resolution macroscopic images were captured by VHX-8000 digital microscope (Keyence, Osaka, Japan)