Villi and crypts

Question 1

What are crypts?

Answer 1

The recessions between the villi.

Question 2

What is the epithelial surface of the villi like?

Answer 2

Simple columnar. There’s numerous microvilli on the villi forming a “brush border”

Question 3

What does each villus contain?

Answer 3

A capillary network which transports absorbed amino acids and monosaccharides plus a blind-ended lymph vessel (or lacteal) that transports absorbed fat. The capillary network eventually drains into the portal vein.

Question 4

What four types of specialised cells are present within the epithelium of the villi?

Answer 4

1. Absorptive cells: they secrete digestive enzymes and absorb nutrients.
2. Goblet cells: these produce mucus that lubricates and protects the epithelium from mechanical damage.
3. Granular cells: these secrete enzymes and protect epithelium from bacteria.
4. APUD cells: these cells produce endocrine secretions that regulate secretion and motility of the GI tract and associated glands.

Question 5

Where do the specialised cells of the villi arise from?

Answer 5

Undifferentiated cells at the base of the crypts.