Observations on small granule cells in adult human bronchial epithelium and in carcinoid and oat cell tumors.

Small granule cells are described in the segmental bronchi of adult humans. Rarely, these cells were seen abutting the lumen of the airway. A luminal location has been described for these cells in the bronchial epithelium of human fetuses and neonates and it is suggested that luminal small granule cells may be a rare, although normal component of the adult human bronchial epithelium. The dense core granules of the small granule cells stained intensely with phosphotungstic and at low pH suggesting that they contain glycoprotein. Granules present in a carcinoid and an oat cell tumor stained similarly. The role of the small granule cell in the genesis of bronchial carcinoid and oat cell tumors is recognized.