Carbohydrate cytochemistry of rhesus monkey tracheal submucosal glands

This study was designed to characterize the ultrastructure and carbohydrate content of secretory cells in submucosal glands of rhesus monkey and to compare this information with that available for humans. The tracheas from five adult monkeys were fixed by airway infusion, processed, and embedded for both light and transmission electron microscopy. Histochemical stains including alcian blue–periodic acid–Schiff, dialyzed iron, and high‐iron diamine‐alcian blue were applied to serial glycol methacrylate sections. The cytochemical stains used included periodic acid‐thiocarbohydrazide–silver proteinate, high‐iron diamine, and low‐iron diamine. The glandular secretory cells were divided into four categories based on ultrastructure and location within the gland. Cells in the first category resembled the mucous cell of the surface epithelium and were located in ducts most proximal to the tracheal lumen. The second category consisted of cells that were located in distal ducts and contained large electron‐lucent granules. The granules in both of these cell groups contained material that was periodate‐reactive and sulfated. Cells of the third category contained granules that were either electron‐lucent or electron‐dense. These cells, which were difficult to characterize as either serous or mucous, were located in secretory tubules and acini and contained periodate‐reactive glyco‐conjugates that were either sulfated or nonsulfated. The last category consisted mainly of cells that contained electron‐dense granules that were lightly periodate‐reactive or a few that were unreactive with any of the cytochemical methods used here. We concluded from this study that 1) the submucosal glands of rhesus monkey contain secretory cells with a variety of morphologies; 2) the secretory cells, which in some cases are not easily identified as mucous or serous, contain material that is periodate‐reactive and sulfated, contain material that is periodate‐reactive only, or contain no carbohydrate as detected by the cytochemical methods used; and 3) the submucosal glands of rhesus monkey trachea resemble those described in human airways.