Tracheal globule leukocytes and subepithelial mast cells: a comparative study in the rat.

We studied some morphologic, histochemical and functional characteristics of rat tracheal granulated cells. These cells are present within the epithelium (globule, leukocytes) and in the subepithelial area (subepithelial mast cells). In the latter, they are mostly concentrated in the membranous part of the mucosa. Both cell types present the main characteristics of mast cells (metachromasia and ability to bind IgE). However, they are distinct from each other in morphological and histochemical criteria and in their response to intensive corticosteroid administration. Marked differences exist between subepithelial mast cells and mast cells from the connective tissue. This raises the hypothesis of the existence of a respiratory counter part to the intestinal mucosal mast cells.