The Normal and Abnormal Pulmonary Neuroendocrine Cell

Feyrter, in 1938 (7) and Frohlich, in 1949 (8) described the presence of “clear” cells in the bronchial mucosa of several mammals. It was postulated that these cells comprise a diffuse system which is involved in paracrine secretion, and perhaps function as chemoreceptors. Subsequently, Bensch et al. (5) studied these cells by electron microscopy, and noted the presence of secretory granules. It now is known that these cells are a component of the diffuse neuroendocrine system found in the gut as well as many other tissues in the body, and that they may have important physiologic and pathologic significance (2).