Fig. 3

Macroscopic and microscopic examinations of tumors in MNU-induced and metformin-treated rat bladders. Macroscopic graphs (A-C): a Bladders from the control group showed a normal appearance; b Bladders from the MNU-induced group had thicker walls and a wider range of tumor lesions (outlined by the dotted line); c Bladders from the metformin-treated group showed some tiny and isolated lesions (indicated by the arrow). Histopathological examinations (D-H): tissue or tumor sections were stained with H & E and analyzed by pathologists double blindly. d Normal uroepithelial cells were observed in the control group; e Low grade and f high grade papillary tumor were found mainly in the metformin-treated group, and (g) CIS and (h) Infiltrative (invasive) tumors were found mainly in the MNU group. No invasive tumors were observed in Met group. i Summary of tumor sizes in the MNU group and Met group. **, P < 0.01 when compared to MNU group. Magnificaiton of micrographs: x100