Microvilli are tiny apical projections that increase surface area; where are they abundant?

• A. Lining of blood vessels
• B. Respiratory tract and fallopian tubes
• C. Intestinal lining and kidney tubules
• D. Skin and hair follicles

Answer: (C)

Microvilli expand the apical surface area of absorptive epithelial cells, boosting how much material can be absorbed or reabsorbed. They are most pronounced where the epithelium handles a lot of uptake. In the intestinal lining, enterocytes are packed with microvilli to form a heavy brush border, giving digestive enzymes close contact with nutrients and a huge surface for absorption. In the kidney, proximal tubule cells have a dense brush border of microvilli that maximizes reabsorption of water, ions, and nutrients from the filtrate.

Lining of blood vessels isn’t specialized for absorption in that way and relies on a thinner, more permeable endothelium rather than a large absorptive surface. The respiratory tract and fallopian tubes use cilia to move mucus or ova rather than rely on microvilli-rich surfaces. Skin and hair follicles serve as protective barriers with little need for extensive surface area from microvilli. So the tissues with abundant microvilli are the intestinal lining and kidney tubules.