Estrogen and tracheal secretion: the effect of estrogen on the epithelial secretory cells of the rat trachea.

Epithelial secretory cells of the tracheal mucosa obtained from ovariectomized control and ovariectomized estrogen-treated rats were studied morphologically by scanning and transmission electron microscopy and by the combined periodic acid Schiff (PAS) and alcian blue (AB) staining method. A significant decrease was observed in the number of large PAS-reactive secretory cells following estrogen treatment. Concomitantly the number of the Mixed+ cells containing both weakly acid and neutral glycoproteins was found to increase significantly. A majority of the observed secretory cells exhibited either an apical protrusion loaded with secretory granules, extending to a maximum distance of 7.9 micrometer into the tracheal lumen or an apical indentation devoid of mature secretory granules, descending to 5.6 micrometer below the luminal surface. The frequency of cells exhibiting an apical indentation was significantly greater in estrogen-treated animals than in controls. The present findings indicate that estrogen treatment of ovariectomized rats results in: 1) an increase in the synthesis of weakly acid glycoprotein within tracheal secretory cells; 2) a concomitant decrease in the frequency of secretory cells containing neutral glycoprotein; and 3) a general increase in the secretion by the tracheal cells.