Which type is a single layer of mostly columnar cells (sometimes combined with squamous or cuboidal cells) with cilia that move debris and mucus?

• A. Ciliated epithelium
• B. Columnar epithelium
• C. Simple cuboidal epithelium
• D. Compound epithelium

Answer: (A)

The key idea is identifying a lining that is a single layer of tall cells with tiny hair-like structures on the surface that move mucus and debris. When you have mostly columnar-looking cells arranged in a single layer and those cells bear cilia, they beat in a coordinated way to push mucus and any trapped particles out of the airway. This is the ciliated epithelium, often described as pseudostratified columnar epithelium because it looks layered due to nuclei at different heights, yet every cell touches the basement membrane. That cilia-driven movement of debris and mucus is the defining feature.

Simply calling it columnar epithelium doesn’t guarantee cilia are present, and simple cuboidal epithelium consists of cube-shaped cells with no cilia. Compound (stratified) epithelium would involve multiple layers, which isn’t indicated here. So the presence of cilia with a single-layer, mostly columnar arrangement points to ciliated epithelium.