The Tracheo-Bronchial Epithelium

Abstract

The upper part of the respiratory tract functions as an air-conducting system. Here, warming and moistening of the inhaled air and the removal of inhaled particles occurs. It is lined by the pseudostratified respiratory epithelium, which consists of four cell types. (1) The columnar ciliated cells, which possess cilia that project from their apical plasma membrane and function in the autonomous, coordinated movement of luminal content. (2) The goblet cells (MC in A), unicellular glands synthesizing and secreting mucus, which forms part of the mucus blanket. The mucus blanket functions as a lubricant and a protective layer. (3) A small number of neuroendocrine cells (also referred to as Kultschinsky cells), dispersed in the epithelium. (4) The basal cells, which function as stem cells for the regeneration of the respiratory epithelium.