The tracheobronchial glands, composed of mucous and serous secretory cells, provide a
mucin-rich, antimicrobial-rich secretion for the conducting airways. The secretory processes
of these cells are under complex neurohumoral control. Several diseases demonstrate
considerable increases in the volume of secretory glands, the amount of glandular
secretions or the character of the secretory product. The role of the tracheobronchial glands
in the pathophysiology of chronic bronchitis, asthma and cystic fibrosis is discussed.