Fig. 2.

Analysis of invasive tongue SCCs from rats exposed to high doses of NQO (20–30 p.p.m.). IHC was performed on SCC sections from 15 non-supplemented controls, 8 low- and 8 high-Zn-supplemented rats. Representative sections were presented [red, 3-amino-9-ethylcarbazole, (AEC)]; brown, 3,3′-diaminobenzidine tetrahydrochloride (DAB), DAB; black, DAB with cobalt chloride). Scale bars, 100 μm (hematoxylin and eosin-stained), 50 μm (PCNA, cyclin D1 and p53), 25 μm (ISOL and COX-2). Arrows show area of high immunostaining of these markers. The cell proliferation-labeling index (PCNA-LI) and apoptosis index (assessed by ISOL assay) and immunoscores (cyclin D1, p53 and COX-2) per ∼800–1000 tumor cells are quantified at right. Bar charts represent mean ± standard deviation. Compared with control: *P < 0.05, **P < 0.01, ***P < 0.001