airway hillock

The airway hillock is a region of squamous epithelium found within the tracheobronchial tree that is continuous with the surrounding tracheobronchial epithelium. It represents a distinct epithelial microstructure within the conducting airways and has been identified as a site involved in airway epithelial biology and potentially in responses to injury.

The airway hillock is located within the tracheobronchial tree, positioned among the respiratory epithelium that lines the trachea and bronchi. It consists of squamous epithelium that is continuous with the adjacent pseudostratified ciliated columnar (tracheobronchial) epithelium, forming a discrete region within the airway wall.

The precise function of the airway hillock is an area of ongoing research. It is thought to be involved in airway epithelial maintenance and possibly in the response to mucosal injury. As a squamous epithelial region within a predominantly columnar epithelial environment, it may represent a specialized niche or transitional zone with roles in epithelial homeostasis.

Because the airway hillock exists within the broader tracheobronchial epithelium, it may be associated with conditions affecting airway mucosa, such as chronic bronchitis, smoke-related injury, or infectious processes. Squamous metaplasia of the airway epithelium, which may be associated with chronic irritation, involves changes in the type of epithelium lining the airways.

The airway hillock is typically identified through histological examination of tracheobronchial tissue sections, using light microscopy with standard staining techniques such as hematoxylin and eosin. Bronchoscopy provides clinical access to the tracheobronchial tree, and biopsies obtained during bronchoscopy can be processed for histological and immunohistochemical analysis to evaluate epithelial structures including the airway hillock.