Histochemical and Cytological Characterizations of Mucosal and Connective Tissue Mast Cells of Mongolian Gerbils (Meriones unguiculatus)

Mast cells in jejunum, skin, and tongue of Mongolian gerbils (Meriones unguiculatus) were examined in terms of their histochemical, enzyme-histochemical, and ultrastructural properties. When glycosaminoglycans of mast cells in jejunum and tongue were characterized by measuring the critical electrolyte concentration, the salt concentration at which 50% of mast cells could be stained was > 1.0 M for those in the jejunum and also in the tongue, indicating that mast cells in both sites contained heparin. Enzyme-histochemical study revealed that mast cells in the jejunum of Mongolian gerbils were strongly positive for chymase and tryptase, whereas those in tongue and skin were essentially negative for both proteases. By electron microscopy, granular morphology and distribution of surface micro folds of mast cells in the jejunum were different from those in the ear skin. After in vivo stimulation with compound 48/80, however, mast cells in both sites showed remarkable degranulation. From these results, although Mongolian gerbils also have distinct mast cell subsets, their phenotypic properties are different from those of the previously known mast cell subsets of other animals.