Human well differentiated colorectal adenocarcinomas expressed low levels of C2-O-sLe
x. (A) Photomicrograph of a tissue section of a well differentiated colorectal adenocarcinoma stained with hematoxylin and eosin, scale bar = 500 μm. (B) A serial section of the same tissue as shown in (A) stained with CHO-131 mAb (15 μg/ml). Red color indicates positive reactivity with the CHO-131 mAb, scale bar = 500 μm. In (A) and (B) the arrow indicates adjacent normal colorectal mucosa. The arrowhead indicates nests of neoplastic cells in the tunica submucosa and muscularis. (C) Another well differentiated colorectal adenocarcinoma stained with CHO-131 mAb. Red color indicates positive reactivity with the CHO-131 mAb, scale bar = 100 μm. (D) Increased magnification of the boxed area shown in (C) demonstrating red stained CHO-131+ cells. Arrows in (D) indicate cytoplasmic and luminal reactivity with CHO-131 mAb, scale bar = 50 μm. (E) Mucosa of normal colorectal epithelium stained with CHO-131 mAb. Note the absence of red color, indicating a lack of reactivity with the CHO-131 mAb, scale bar = 150 μm. (F) A serial section of the same tissue as in (C) and (D), stained with CEA mAb (1.6 μg/ml). Brown color indicates positive reactivity with CEA mAb, scale bar = 100 μm. All tissue sections were 4 μm thickness. Figures (A) and (B) 20× magnification, (C) 200× magnification, (D) 400× magnification, (E) 100× magnification, and (F) 200× magnification. Mayer's hematoxylin was used as a counterstain for tissues stained with CHO-131 and CEA mAbs. Representative sections from multiple stained tissues are shown.