Formation of stimulus-induced vacuoles in serous cells of tracheal submucosal glands

Parenchymal cells of exocrine glands have been reported to develop numerous large vacuoles when intensely stimulated either pharmacologically, electrically, or physiologically. We have found that tracheal submucosal glands of the cat form similar vacuoles in response to alpha-adrenergic stimulation. Light and electron microscope examination of tracheal submucosal glands stimulated in vitro with methoxamine (10(-4) M) reveals that only serous cells of the gland acini develop vacuoles. Ductal cells and mucous acinar cells do not form vacuoles. Furthermore, several lines of evidence indicate that within serous cells vacuoles arise from secretory granules, which apparently swell as they accumulate fluid during intense stimulation. The following paper describes some of the factors and characteristics of stimulus-induced vacuolation.