Figure 7. The mechanism of action of TiO2-NPs on BTB. TiO2-NPs damage the BTB via three mechanisms. TiO2-NPs interfere with BTB-associated proteins, induce cytoskeletal reorganization, and trigger oxidative stress to perturb TJ proteins. The BTB gap (size X) is expanded (size Y) by TiO2-NPs, and TiO2-NPs (particle size Z<Y) with particle sizes less than Y pass directly through the BTB gap and subsequently affect spermatogenesis. N: nucleus; MF: microfilament.