Which epithelium is typically involved in movements of mucus via ciliary action?

• A. Pseudostratified ciliated columnar epithelium.
• B. Simple squamous epithelium.
• C. Stratified squamous epithelium.
• D. Transitional epithelium.

Answer: (C)

Movement of mucus by ciliary action is carried out by a ciliated epithelium that lines the respiratory tract. This tissue is pseudostratified ciliated columnar epithelium, where the cells appear to be in multiple layers but all reach the surface, and many have apical cilia. The coordinated beating of these cilia propels mucus upward, helping to clear trapped dust, microbes, and other debris. Goblet cells interspersed in this layer produce mucus to trap particles and keep the airway moist. The other options lack this ciliated, mucus-producing arrangement: simple squamous is thin for diffusion, stratified squamous provides robust protection in areas like the skin and mouth, and transitional epithelium accommodates stretching in the urinary tract.