What is the dominant epithelium of the epididymis and its unique feature?

• A. Stratified squamous epithelium with keratinization.
• B. Simple cuboidal epithelium with cilia.
• C. Pseudostratified columnar epithelium with stereocilia; tall principal cells with apical stereocilia.
• D. Transitional epithelium.

Answer: (C)

The epididymis is lined by pseudostratified columnar epithelium with tall principal cells that bear apical stereocilia. These stereocilia are long, non-motile projections, not true cilia, which greatly increase the surface area for absorption and secretion. This specialization lets the epididymis modify the luminal fluid and nourish maturing sperm as they pass through, aiding fluid reabsorption and concentration while supporting sperm maturation. The basal cells maintain the epithelium. This combination—pseudostratified columnar arrangement plus apical stereocilia on tall cells—is what distinguishes the epididymis from regions with keratinized stratified squamous or transitional epithelium.