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Histological findings of tongue in mice treated with 4NQO during 16 weeks. a Normal tongue with no histopathological changes 24 weeks after starting the experiment. b Mild dysplasia after 24 weeks. c Moderate dysplasia after 28 weeks. d Severe dysplasia after 28 weeks. e Invasive squamous cell carcinoma after 32 weeks. Original magnification ×10
