goblet-cell hyperplasia and bronchial hyper-reactivity. Dendritic cells (DCs) sample the airway luminal content for the presence of allergens by crossing the airway epithelial-cell barrier.

The trachea has a number of adaptations: cartilage rings in the walls of the trachea help to keep it open ciliated epithelium and goblet cells to ... parts of the respiratory system as shown ...