Discriminating two types of SA α2,3-Gal receptors in bronchiole (A) and colon (B) by FITC labelled MAA I (green), and biotinylated MAA II (red) receptors. In bronchiole, MAA I and MAA II typically show similar binding intensity, with prominent presence of MAA I on the epithelial lining (Aii). In colon, MAA II binding, mainly localised to goblet cells, dominates MAA I; MAA I binding is seen as a fine line bordering the epithelium (Bii). 1. epithelial lining, 2. mucosa, 3. smooth muscle, 4. goblet cell. Scale bar = 75 μm.