Which of the following is NOT one of the three main epithelial cell shapes?

• A. Squamous
• B. Cuboidal
• C. Pseudostratified
• D. Columnar

Answer: (C)

The main idea is that epithelial tissue is categorized by cell shape. The three basic shapes are squamous (flat and thin), cuboidal (cube-like), and columnar (tall and column-shaped). These shapes align with function: squamous cells excel where rapid diffusion and filtration occur; cuboidal cells support secretion and absorption; columnar cells often provide protection plus absorption or secretion, sometimes with microvilli or cilia to aid these processes.

Pseudostratified describes appearance rather than a distinct shape. In pseudostratified epithelium, nuclei lie at different levels within the same single layer, so it looks stratified, but every cell actually contacts the basement membrane. Many pseudostratified epithelia are columnar in shape and frequently ciliated, such as in the respiratory tract. Because this term reflects an arrangement, not a standalone shape category, it isn’t counted among the three main epithelial shapes.