Fig. 3
Characteristics of fibrotic pulmonary dust foci (fPDF) in rat lungs after inhalation exposure to TiO2 NP (8 mg/m3). A: H&E image of the lesion shown in Fig. 2C. The particles show birefringence in polarized light (B). Masson Trichrome staining (C) and EVG staining (D) of the same area show increased collagen fiber deposition within the lesion, but no changes in elastic fibers were observed. Double staining (E) for the AT2 marker LPCAT1 (green in the cytoplasm) and the AT1 marker Pdpn (brown in the cell membrane) and triple staining (F) for the airway neuroendocrine cell marker CGRP (green in the cytoplasm), the airway club cell marker CCSP (brown in the cytoplasm), and the bronchial epithelial lineage marker Sox2 (red in the nucleus). Staining showed that the epithelium comprising the inside of the lesion was of alveolar cell lineage. bar: 200 μm