Which statement is true about keratinizing stratified squamous epithelium?

• A. It contains a surface layer of dead cells filled with keratin
• B. It has a surface layer of living cells filled with keratin
• C. It is a pseudostratified epithelium
• D. It lacks keratin entirely

Answer: (A)

In keratinizing stratified squamous epithelium, the outermost cells are dead and filled with keratin, forming a tough, waterproof surface. Cells in the deeper layers are alive and proliferate, pushing older cells toward the surface where they accumulate keratin and eventually lose their nuclei. That’s why the surface layer is composed of dead, keratin-filled cells.

Saying the surface is made of living cells filled with keratin would be incorrect because keratinization leads to cell death at the surface. Pseudostratified describes a different arrangement where nuclei appear at different levels in what looks like multiple layers, not true stratified squamous epithelium. And lacking keratin is inconsistent with keratinizing epithelium, which by definition contains keratin in the surface cells.