CD133 expression in normal and neoplastic tissues. Epithelial tissues and tumors: A) normal colon mucosa, B) colon adenoma, C) colon adenocarcinoma, D) normal mammary gland, E) mammary adenoma, F) mammary carcinoma. Non-epithelial malignant tissues: G) brain glioblastoma multiforme, H) gastrointestinal stromal tumor, I) myelogenous leukemia soft tissue infiltrate. Germ cell neoplasias of the testis: J) Intratubular germ cell neoplasia, K) seminoma, L) embryonal carcinoma. Note the apical/endoluminal membrane staining in epithelial tissues (A, D) and in neoplasias with tubule-forming tumor cells (B, C, E, F, L). In solid tumors without tubular structures there is perinuclear or diffuse cytoplasmic staining (G-K). A = ×200, scale bar = 100 μm. B, C = ×100, scale bar in A = 200 μm. D-F, H, J-L = ×400, scale bar in A = 50 μm. G, I = ×1000, scale bar in A = 20 μm.