Titanium Dioxide Nanoparticles (TiO2-NPs) applications are widely used in the daily life and their potential
toxicity to the living organism is necessary to be insured. The nanomaterial may or may not exhibit the same toxic
potential as the original material. Therefore, this study used TiO2-NPs and their original bulk to ensure their safety
on the histology, immunohistochemistry and ultrastructure of the liver of male albino mice (Mus musculus). For this
purpose, 25 and 50 mg/kg b.wt.; 55 μm size; anatase TiO2-NPs compared with 50 mg/kg b.wt.; 106 μm size; anatase
TiO2 micro-sized (bulk form) were daily injected intraperitoneally into the mice for ten successive days. The results
showed numerous alterations in the liver of anatase TiO2-NPs treated animals in a dose-dependent manner that
were more than these shown in anatase TiO2-bulk material. However, histopathological disruption of the normal
cellular architecture of liver, vacuolization and congestion of blood capillary following higher doses of TiO2-NPs
exposure were revealed. In addition, quantitative analysis of both Bcl-2 and PCNA immunostaining density data
showed significant increase as compared with the control indicating activation of apoptosis and proliferation in liver
cells. Moreover, ultrastructural observation displayed dramatic potential alteration in nucleus, mitochondria, rER,
numerous lysosomes, bile canaliculi and a Kupffer cell was detected. Besides, obvious agglomerations of TiO2-NPs
were taken up by hepatocytes cytoplasm and its organelles, nucleus and kupffer cells. These results show that
TiO2-NPs induced potential toxicity in mice liver following both doses used that varied severely when compared with
TiO2-bulk form. Therefore, it could be concluded that both tested doses of nano-anatase TiO2 induced potential liver
toxicity than the dose of bulk anatase TiO2.