Comparative histochemistry of gastrointestinal mucosubstances

Two histochemical sequential staining techniques, Alcian blue-PAS (AB-PAS) and high-iron-diamine-Alcian blue (HID-AB), which differentiate neutral from sulfated and non-sulfated acid mucosubstances, were applied to sections from the gastrointestinal tract of eleven mammalian species, including man, to study patterns of distribution of gastrointestinal epithelial mucosubstances. The application of these techniques under uniform laboratory conditions enabled a detailed description of epithelial mucosubstances throughout the gastrointestinal tract relative to location in each species as well as a comparison of their distribution among various species. The results showed that all of the 11 species studied had a distinctly different distribution of epithelial mucosubstances throughout the entire gastrointestinal tract. These differences were most obvious in the stomach and duodenum. In each species, neutral mucosubstances were most evident in the stomach and acid mucosubstances in the intestines, with sulfomucins most prominent in the large bowel. Acid mucosubstances were noted in Paneth cell granules of rodent species only. These histochemical observations make available a uniform comparative basis for the normal distribution of mammalian gastrointestinal mucosubstances which should facilitate their study in diverse pathological conditions.