What is a key characteristic of pseudostratified columnar epithelium?

Pseudostratified columnar epithelium is characterized by its unique structure, where it appears to have multiple layers due to the varying heights of its cells. However, a key detail is that all cells in this type of epithelium do reach the basement membrane, making it technically a single layer. This characteristic contributes to its functionality, particularly in the respiratory tract where it is often ciliated, assisting in the movement of mucus and trapped particles.

The distinction is critical because while the arrangement gives an illusion of stratification, the fact that every cell reaches the basement membrane is what defines it as a single-layered epithelium. The cells may be irregular in height, contributing to the "pseudostratified" name, but fundamentally, they are all anchored to the same basal surface. This structure allows for effective secretion and movement of substances across the epithelial surface.