Two major types of mucins can be readily distinguished by histochemical methods, i.e. acid and neutral mucins (glycoconjugates). A significant advance in the histological detection of mucins was achieved by the introduction of stainings such as the periodic acid-Schiff (PAS) and Alcian blue at pH 2.5, Alcian blue at pH 1.0 and high iron-diamine/Alcian blue as staining agents. Alcian blue 8GX is primarily used for the detection of acid mucins.