Question

Brush border of small intestine cells is formed of ____________.

• A. Microvilli
• B. Cilia
• C. Villi
• D. Circular folds

Answer 1

The correct option is A Microvilli

1. The innermost layer lining the lumen of the alimentary canal is the mucosa. This layer forms irregular folds (rugae) in the stomach and small finger-like foldings called villi in the small intestine.
2. The cells lining the villi produce numerous microscopic projections called microvilli giving a brush border appearance found on the apical surface of some epithelial cells. These modifications increase the surface area enormously and help in secretion and absorption.
3. Microvilli are covered in the plasma membrane, which encloses cytoplasm and microfilaments. Though these are cellular extensions, there are little or no cellular organelles present in the microvilli. Hence, the brush border of small intestine cells is formed of microvilli.
   

So, the correct answer is 'microvilli'.