ABSTRACT

In 1938, an Austrian pathologist, Friedrich Feyrter, published a monograph (1) in which he described a system of regulatory cells, a ‘‘diffuse endocrine epithelial organ,’’ distributed throughout the various organs and exerting an influence upon them by local release of chemical messengers, a mode of secretion he called ‘‘paracrine.’’ This was not a fundamentally new idea (2,3), but Feyrter was the first to suggest that such cells were ubiquitous throughout the tissues, constituting a unified system of local endocrine control. This concept was consolidated largely by the work of Pearse and colleagues in the late 1960s (4-7), and the existence of what is now generally known as the diffuse neuroendocrine system (DNS), the cells of which are characterized by the secretion of amine, protein, and peptide hormones that are stored in cytoplasmic dense core (neurosecretory) vesicles (DCVs) (Fig. 1), has became universally accepted. It is with the pulmonary component of this system, its structure and function in healthy lungs, and the changes it undergoes in pulmonary disease that the first two sections of this chapter are concerned.