Small Intestinal Mucosa

**Semantic type:** Tissue

**Definition:** Mucosa arranged into two fundamental structures - villi and crypts of Lieberkuhn. Villi are projections into the lumen of the small intestine, covered with simple columnar epithelium. Crypts of Lieberkuhn are moat-like invaginations of the epithelium around the villi that extend through the lamina propria down to the muscularis mucosae. Lymphocytes often invade the epithelium or form solitary lymphoid nodules in the lamina propria. Lymph nodules may form longitudinal aggregations of 30-50 nodules in the lamina propria of the ileum. These large aggregations are called Peyer's patches. The muscularis mucosae has two layers and extends into the intestinal villi, where the smooth muscle cells form a longitudinal bundle in the centre of the villi. The small intestinal mucosa secretes gastrin, somatostatin, cholecystokinin and secretin.

**Synonyms:** - SMALL INTESTINAL MUCOSA - Small Bowel Mucosa - mucosa of organ of small bowel - mucosa of organ of small intestine - mucosa of small bowel - mucosa of small intestine - mucous membrane of small bowel - mucous membrane of small intestine - organ mucosa of small bowel - organ mucosa of small intestine - small bowel mucosa - small bowel mucosa of organ - small bowel mucous membrane - small bowel organ mucosa - small intestinal mucosa - small intestine mucosa - small intestine mucosa of organ - small intestine mucous membrane - small intestine organ mucosa - tunica mucosa (intestinum tenue) - tunica mucosa intestini tenuis