In the intestine, which layer contains enterocytes with microvilli, and what is its function?

• A. The mucosa (simple squamous epithelium) for nutrient absorption and digestion.
• B. The submucosa; secretes mucus to lubricate.
• C. The muscularis externa; peristalsis.
• D. The serosa; provides lubrication.

Answer: (C)

Enterocytes with microvilli are located in the mucosa of the small intestine, on the simple columnar epithelium that lines the intestinal villi. This mucosal layer is where nutrient absorption occurs. The microvilli form a brush border that massively increases surface area and houses membrane-bound digestive enzymes, allowing digestion to finish at the cell surface and enabling nutrients to be transported into enterocytes for entry into the bloodstream or lymphatics. The other layers—submucosa, muscularis externa, and serosa—do not contain this absorptive epithelium; they support movement, secretion, and lubrication rather than absorption.