What best describes the function of microvilli in epithelial cells?

• A. Move substances via cilia
• B. Increase surface area for absorption
• C. Provide mechanical strength via desmosomes
• D. Secrete mucus.

Answer: (B)

Microvilli increase the membrane surface area of epithelial cells, especially in the intestine and kidney, forming a brush border that greatly boosts absorption. By packing many tiny projections into the apical membrane, there are more sites for nutrient transporters and digestive enzymes to act, making nutrient uptake more efficient. They’re supported by an actin filament core, but they’re not motile like cilia, so they don’t move substances themselves. They also don’t give mechanical strength between cells—that’s the job of desmosomes—and they don’t secrete mucus, which is produced by goblet cells. So their primary function is to maximize surface area for absorption.