Small Intestine, mucosa (cross section of jejunum)
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The mucosa of the small intestine is lined by simple columnar epithelium which evaginates into villi (green outlines) and invaginates into crypts (blue outlines).
Note (yellow arrowheads) that epithelium of villi is continuous with that of adjacent crypts, even though some crypts appear "disconnected" due to plane of section.
Lamina propria of the small intestine forms the core of villi and surrounds the crypts. A long "empty" space within the lamina propria, especially if lined by simple squamous endothelium, is a lacteal.
The muscularis mucosa of the small intestine forms a thin layer (only a few muscle fibers in thickness) beneath the deep ends of the crypts.
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SIUC / School
of Medicine / Anatomy / David
Last updated: 28 December 2001 / dgk