Figure 2. (A) Histopathological images stained with hematoxylin and eosin (H&E) and (B) Expression of MMP-9, MMP-2, and TIMP-2 by immunohistochemistry. Tissues were fixed on slides and stained with H&E. Expression was detected using primary antibodies specific to each analyte (Abcam). (A1-A2) Normal adjacent squamous mucosa used as control tissue, showing stratified squamous epithelium on the surface with underlying connective tissue from the posterior region of the oral tongue (100*). (A3-A4) Infiltrative squamous cell carcinoma, showing connective tissue invasion, inflammatory infiltrate, and keratin pearl formation (100*). (B1-B3) Immunohistochemical expression in normal adjacent mucosa (control): (B1) MMP-9, positive cytoplasmic staining in the basal epithelial layer (100*), (B2) MMP-2, weak (1+) cytoplasmic expression in the basal epithelial cells (100*), (B3) TIMP-2, positive expression in epithelial basal cells and connective tissue (100*). (B4-B6) Expression in tumor tissue: (B4) MMP-9, strong cytoplasmic expression in malignant epithelial cells (100*), (B5) MMP-2, weak cytoplasmic expression (1+) in tumor epithelial cells (40*), and (B6) TIMP-2, positive cytoplasmic staining in carcinoma cells and inflammatory infiltrate (100*). Scale bar: 200 μm.