Which tissue type appears to be multi-layered but is a single layer of cells with nuclei at different levels?

Which tissue type appears to be multi-layered but is a single layer of cells with nuclei at different levels?

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

Answer: (C)

Pseudostratified columnar epithelium is the type that looks like it has multiple layers because the nuclei are at different heights, but it’s actually a single layer since every cell contacts the basement membrane. The cells vary in height, so some don’t reach the surface, giving a false layered appearance. This arrangement is typical of parts of the respiratory tract, like the trachea, where the cells are often ciliated and may include goblet cells to produce mucus. In contrast, simple squamous epithelium is a true single layer of flat cells with nuclei generally in a similar plane, not at varying levels. Simple columnar epithelium is a single layer of tall cells with nuclei near the base, not at differing heights. Transitional epithelium can appear multi-layered and changes shape with stretch, but it’s not a simple single layer with nuclei at different levels.

Pseudostratified columnar epithelium is the type that looks like it has multiple layers because the nuclei are at different heights, but it’s actually a single layer since every cell contacts the basement membrane. The cells vary in height, so some don’t reach the surface, giving a false layered appearance. This arrangement is typical of parts of the respiratory tract, like the trachea, where the cells are often ciliated and may include goblet cells to produce mucus.

In contrast, simple squamous epithelium is a true single layer of flat cells with nuclei generally in a similar plane, not at varying levels. Simple columnar epithelium is a single layer of tall cells with nuclei near the base, not at differing heights. Transitional epithelium can appear multi-layered and changes shape with stretch, but it’s not a simple single layer with nuclei at different levels.