Ileum

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. Ileum can be distinguished from jejunum by finger shaped villi of ileum as opposed to tongue shape of jejunum.

Roll over mouse

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 not many villi as in the duodenum but they are finger-shaped and are as tall as entire section.
c. Plicae circualres are tall and few and the crypts of Lieberkuhn are also tall.
d. Simple columnar epithelium covers the surface and there are NO special 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 since ileum is a hollow 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 villi which picks up all structures in the gut which present with villi or villi like structures and they include duodenum, ileum and jejunum. With tall villi, it eliminates other structures and selects only jejunum and ileum. Finger shaped villi picks only ileum and eliminates jejunum.

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