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Intestinal villi (sg.: villus) are small, finger-like projections that extend into the lumen of the small intestine. Each villus is approximately 0.5–1.6 mm in length (in humans), and has many microvilli projecting from the enterocytes of its epithelium which collectively form the striated or brush border. Each of these microvilli are about 1 ...
The normal thickness of the small intestinal wall is 3–5 mm, [6] and 1–5 mm in the large intestine. [7] Focal, irregular and asymmetrical gastrointestinal wall thickening suggests a malignancy. [ 7 ]
During each mitosis, one of the two daughter cells remains in the crypt as a stem cell, while the other differentiates and migrates up the side of the crypt and eventually into the villus. These stem cells can differentiate into either an absorptive (enterocytes) or secretory (Goblet cells, Paneth cells, enteroendocrine cells) lineages. [3]
Subsets of sensory intestinal epithelial cells synapse with nerves, [9] and are known as neuropod cells. [10] Paneth cells produce antimicrobial peptides such as human alpha-defensin. [11] [12] Microfold cells (commonly referred to as M cells) sample antigens from the lumen and deliver them to the lymphoid tissue associated with the mucosa (MALT).
Foot-like processes are also present in Müller glia (modified astrocytes of the retina), [3] pancreatic stellate cells, [4] dendritic cells, [5] oligodendrocytes, [6] and others. Microglia , which are notably smaller than macroglia , can also extend their end-processes to contact areas of capillaries that are devoid of astrocyte endfeet , and ...
The villi of the jejunum look like long, finger-like projections, and are a histologically identifiable structure. While the length of the entire intestinal tract contains lymphoid tissue , only the ileum has abundant Peyer's patches , which are unencapsulated lymphoid nodules that contain large numbers of lymphocytes and immune cells, like ...
Smooth muscle fibers may be in the lamina propria, such as in the intestinal villi. It is practically void of fat cells. [4] Lymphatics penetrate the mucosa and lie below the basement membrane of the epithelium, from there they drain the lamina propria. [8] The fast rate of cell death and regeneration of the epithelium leaves behind many ...
The muscularis mucosae (or lamina muscularis mucosae) is a thin layer of muscle of the gastrointestinal tract, located outside the lamina propria, and separating it from the submucosa. It is present in a continuous fashion from the esophagus to the upper rectum (the exact nomenclature of the rectum's muscle layers is still being debated).