Which epithelium protects underlying tissues in areas subject to abrasion?

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

Answer: (D)

When tissues face constant rubbing or friction, a multilayered, tough outer surface provides the best protection. Stratified squamous epithelium has several layers of cells, with the outermost layer being flat and protective. This arrangement lets the deeper cells continually replace those shed from the surface, so the tissue can withstand abrasion without exposing the underlying tissues. In skin, the outermost cells often accumulate keratin, creating a hard, water-resistant barrier that resists wear. In moist areas such as the mouth, esophagus, or vagina, the nonkeratinized form remains protective while staying flexible and hydrated, which is important for daily use and function.

Simple squamous epithelium, by contrast, is a single cell layer ideal for diffusion and filtration, not for withstanding repeated rubbing. Pseudostratified columnar may look layered but primarily serves roles in secretion and transport in specific tracts, not broad abrasion resistance. Transitional epithelium is specialized for stretching, found in the urinary system, and not the typical protective barrier against friction.