Colon

Cell types: Absorptive, Paneth, goblet, mesothelial, enteroendocrine cells

Differential diagnosis:
Other columnar epithelium of the rest of the gut tube can be distinguished from the duodenum by their submucous glands. There are no pits in the ileum. Jejunum can be distinguished from ileum by finger shaped villi of ileum as opposed to tongue shaped villi of jejunum. The colon has no villi at all and can be distinguished from other non villi structures such as esophagus (squamous epithelium) by surface epithelium type.

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Diagnostic Features:
a. Tissue is hollow and presents with a large lumen which fills more than 1/10th of low power field.
b. There are no villi
c. There are prominnet crypts of Lieberkuhn and very thin muscualris externa in view of the formationof islonitudinal portion into tenia coli bands.
d. Simple columnar epithelium covers the surface and there are NO special submucous glands of Brunner.

Draw your own section here and make your diagnosis by data base selection below

Database selection:

Practical

Tissue

Gross

Level 1: Select hollow sincethe colon is a holow organ.
Level 2: Select large as opposed to small since lumen fills more than 1/10th of low power field for tissues of rat to man. This will select from database both cartilage and non cartilage containing tubes.
Level 3: Select no cartilage. This eliminates the trachea and other respiratory tract tubes and selects mainly digestive system organs.
Level 4: Select no villi which picks up all structures in the gut which present without villi and they include colon, rectum and anus.

Columnar epithelium picks out rectum and colon and automatically eliminates esophagus.

Note the musculature of the muscularis externa. Can you identity the tall plicae circulares and the crypts of Lieberkuhn?