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The lamina propria may also be rich in vascular networks, lymphatic vessels, elastic fibers, and smooth muscle fascicles from the muscularis mucosae. Afferent and efferent nerve endings can be found in the lamina propria as well. [6] Immune cells as well as lymphoid tissue, including lymphoid nodules and capillaries, may be present.
Both GALT and mesenteric lymph nodes are sites where the immune response is started due to the presence of immune cells through the epithelial cells and the lamina propria. The GALT also includes the Peyer's patches of the small intestine, isolated lymphoid follicles present throughout the intestine and the appendix in humans. [2]
If mucosal barrier homeostasis has not been violated and invasive pathogens are not present, dendritic cells induce tolerance in the gut due to induction of Tregs by secretion of TGF-β and retinoic acid. [17] These Tregs further travel to the lamina propria of villi through lymphatic vessels.
In the ileum there are occasionally Peyer's patches in the lamina propria. Brunner's glands are found in the duodenum but not in other parts of the small intestine. [1] In the colon, epithelium is simple columnar and without villi. Goblet cells, which secrete mucus, are also present. [1]
The mucosa is composed of one or more layers of epithelial cells that secrete mucus, and an underlying lamina propria of loose connective tissue. [1] The type of cells and type of mucus secreted vary from organ to organ and each can differ along a given tract. [2] [3]
These cells are known to initiate mucosal immunity responses on the apical membrane of the M cells and allow for transport of microbes and particles across the epithelial cell layer from the gut lumen to the lamina propria where interactions with immune cells can take place. [1]
Colorectal adenocarcinoma is distinguished from a colorectal adenoma (mainly tubular and ⁄or villous adenomas) mainly by invasion through the muscularis mucosae. [10] In carcinoma in situ (Tis), cancer cells invade into the lamina propria, and may involve but not penetrating the muscularis mucosae. This can be classified as an adenoma with ...
Gastric erosion occurs when the mucous membrane lining the stomach becomes inflamed. Specifically, the term "erosion," in this context means damage that is limited to the mucosa (which consists of three distinct layers: The epithelium (in the case of a healthy stomach, this is non-ciliated simple columnar epithelium), basement membrane, and lamina propria).