epithelial cell of tracheobronchial tree basal epithelial cell of tracheobronchial tree 2010-09-20T02:10:36Z The basal epithelial cells of the tracheobronchial tree are critical components found in the lining of the airway passages, including the trachea and bronchi. They are keratin-5-positive, nonciliated, cuboidal cells and typically tightly attached to the basement membrane. In humans, the proportion of basal cells in the respiratory epithelium gradually decreases going down the tracheobronchial tree: they represent approximately 34% of the cells in the trachea, 27% in the large airways, and 10% in the small airways, although it is worth noting that there are differences in the compositions of the tracheobronchial epithelia between different species. Basal epithelial cells serve as the basal layer of the tracheobronchial epithelium, providing both structural and regenerative support for the epithelial tissue that lines the upper regions of the respiratory tract. They serve as progenitor or stem cells that are capable of differentiating into multiple cell types, such as ciliated and secretory cells. This gives them a central role in homeostatic maintenance of the epithelium, and in repairing damaged epithelium after an injury or during disease. This regenerative capacity is crucial in maintaining the integrity of the tracheobronchial surface, especially given its continual exposure to inhaled irritants and microorganisms. In addition to their primary restorative function, basal epithelial cells are also involved in the initial immune response within the tracheobronchial tree. Equipped with pattern recognition receptors, these cells can identify and respond to pathogenic organisms, triggering an immune response and producing a range of inflammatory mediators, such as cytokines and chemokines, to help combat infections. (This extended description was generated by ChatGPT and reviewed by the CellGuide team, who added references, and by the CL editors, who approved it for inclusion in CL. It may contain information that applies only to some subtypes and species, and so should not be considered definitional.) An epithelial cell type that lacks the columnar shape typical for other respiratory epithelial cells. This cell type is able to differentiate into other respiratory epithelial cells in response to injury.