Which of the following is NOT a characteristic of typical respiratory epithelium?

The correct choice is indeed the option that states "Contains layers." Typical respiratory epithelium is classified as pseudostratified columnar epithelium, meaning that while it appears to have multiple layers of cells due to the varying heights of the nuclei, it is actually a single layer of cells. Each cell touches the basement membrane, which distinguishes it from truly stratified epithelium that consists of multiple cell layers.

In contrast, the other characteristics listed—ciliated cells, goblet cells, and basal cells—are integral components of typical respiratory epithelium. Ciliated cells help move mucus and trapped particles out of the airways, facilitating the cleaning of the respiratory tract. Goblet cells produce mucus, which serves to trap dust, pathogens, and other particles, providing an essential defense mechanism for the respiratory system. Basal cells are important for the maintenance and regeneration of the epithelium, serving as progenitor cells that can differentiate into other cell types as needed. Thus, these elements contribute to the overall function and integrity of the respiratory epithelium, while the notion of having multiple layers does not apply to this specific type of epithelium.