Figure 1: A photomicrograph of the buccal mucosa of rat treated by 10 mg/kg methotrexate (A1,H& E x100; A2,H&E x400) showing increase in the thickness of the epithelium, 20 mg/kg methotrexate (B1,H&E x100; B2,H&E x 400) showing increase in the thickness of the epithelium and the number of subepithelial inflammatory cells and blood vessels, 40 mg/kg methotrexate (C1,H&E x 100; C2, H&E x 400), showing increase in the thickness of the epithelium and the number of subepithelial inflammatory cells and congested blood vessels (arrows).