Fig. 3.

Transmission electron micrographs of lavaged cells at 24 h from rats instilled with NPs at a dose of 1 mg/kg body weight. Macrophage uptake was scored as +, ++, or +++ when 1–2, 3–4 or ≥5 particle-containing phagosomes were observed in macrophages, respectively. a CeO₂, b Si-CeO₂, c BaSO₄ and d. ZnO. No identifiable ZnO NPs were observed in lavaged cells from ZnO-instilled rats. e Morphometric analysis of macrophage uptake of NPs (n = 248, CeO₂, n = 273, Si-CeO₂, n = 295, BaSO₄, n = 250, ZnO). A significantly smaller fraction of lavaged macrophages showed uptake of BaSO₄ NPs compared with CeO₂ and Si-CeO₂ NPs. Data are mean ± SE of % of macrophages (n = 3 rats per NP). * P < 0.05, BaSO₄ vs. CeO₂ and Si-CeO₂ NPs