Hematoxylin and eosin staining of mucins of the gastrointestinal tract

An infrequent observation of assessing hematoxylin and eosin sections is the blue staining of mucins (for example those in goblet cells). This is believed to be due to a low concentration of alum and high pH of the hematoxylin staining solution. This study examines the incidence of blue mucin in various sites of the gastrointestinal tract using a low alum, high pH hematoxylin solution. The results are compared with a conventional hematoxylin solution, iron alum celestine blue method and an alcian blue (pH 2.5)-periodic acid-Schiff (AB-PAS) stain to characterize the type of mucin demonstrated. This study is the first to offer evidence that blue-stained mucin with low alum, high pH hematoxylin corresponds with carboxylated mucins as shown by the AB-PAS stain in the gastrointestinal tract. Iron alum celestine blue was also found to stain the mucin of a proportion of rectal biopsies and appendix as well as the carboxylated mucin of one duodenal biopsy.