Fig. 2

Transmission electron microscopic (TEM) images of BEAS-2B cells without treatment (A), and after a 6-h exposure to 111 µg/ml of coarse (B) and fine (C) U-CNF, fine C-CNF (D), and fine E-CNF (E, F). One cell shows a large mass of fine E-CNF inside the cytoplasm (F). CNFs are indicated by black arrows. VC: vacuoles; LD: lipid droplets (N = 15–20 independent observations)