Small Intestine Cross Section Under the Microscope

Small Intestine (Cross Section)

This is a cross section of the small intestine stained with H&E. It shows the finger-like villi that absorb food and the layers that make up the wall of the digestive tract.

This is a cross section of the small intestine, stained with H&E (hematoxylin and eosin), which colors nuclei purple and most other tissue pink. The inner lining, the mucosa, has finger-like villi that reach into the open center. The villi add surface area for taking in nutrients. At their base are tube-shaped glands called crypts, which hold pale goblet cells that make mucus. Beneath the mucosa lies the submucosa, a layer of connective tissue, and then thick bands of smooth muscle that push food along.

Labeled small intestine under the microscope

Labeled small intestine wall under the microscope showing a villus, crypts, the muscularis mucosae, the submucosa and the inner circular and outer longitudinal muscle layers — One side of the small intestine wall, about 2.6 millimeters across, stained with H&E: villi and crypts in the lining, then the submucosa and the two layers of smooth muscle.

Villus: Finger-like fold reaching into the open center
Crypt: Tube-shaped gland at the base of the villi, cut across
Muscularis mucosae: Thin band of muscle at the base of the lining
Submucosa: Loose connective tissue with blood vessels
Inner circular muscle: Thick band of smooth muscle
Outer longitudinal muscle: Thinner outer band of smooth muscle

What to look for

Villi: Finger-like folds sticking into the open center (lumen).
Simple columnar epithelium: A single layer of tall cells lining each villus, with purple nuclei lined up near their base.
Goblet cells: Pale, cup-shaped cells among the lining cells that make mucus.
Crypts: Tube-shaped pockets between the bases of the villi.
Submucosa: A layer of loose pink connective tissue below the lining.
Muscularis externa: Two layers of smooth muscle, an inner circular one and an outer longitudinal one.

Questions and answers

What does the small intestine look like under a microscope?

The small intestine wall has finger-like villi lining the inside, covered by a single layer of tall cells with pale goblet cells mixed in. Below that are the submucosa and two layers of smooth muscle.

Why does the small intestine have villi?

Villi greatly increase the surface area for absorbing nutrients. The cells on the villi also have tiny projections called microvilli, which add even more surface area.

What are the layers of the small intestine wall?

From the inside out, the layers are the mucosa (lining with villi), the submucosa (connective tissue), the muscularis externa (two layers of smooth muscle), and the serosa (a thin outer covering).

Compare it

How to identify tissue types

Category: Histology and Tissue
Scan magnification: 20x
Stain: H&E

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