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The intestinal epithelium is the single cell layer that forms the luminal surface (lining) of both the small and large intestine (colon) of the gastrointestinal tract.Composed of simple columnar epithelium its main functions are absorption, and secretion.
The epithelium, the most exposed part of the mucosa, is a glandular epithelium with many goblet cells. Goblet cells secrete mucus, which lubricates the passage of food along and protects the intestinal wall from digestive enzymes. In the small intestine, villi are folds of the
The small intestine is the site where most of the nutrients from ingested food are absorbed. The inner wall, or mucosa, of the small intestine, is lined with intestinal epithelium, a simple columnar epithelium. Structurally, the mucosa is covered in wrinkles or flaps called circular folds, which are considered permanent features in the mucosa.
Enterocytes, or intestinal absorptive cells, are simple columnar epithelial cells which line the inner surface of the small and large intestines. A glycocalyx surface coat contains digestive enzymes. Microvilli on the apical surface increase its surface area.
Intestinal glands are found in the epithelia of the small intestine, namely the duodenum, jejunum, and ileum, and in the large intestine (colon), where they are sometimes called colonic crypts. Intestinal glands of the small intestine contain a base of replicating stem cells , Paneth cells of the innate immune system , and goblet cells , which ...
The intestinal epithelium is composed of a single layer of cells and serves two crucial functions. First, it acts as a barrier, preventing the entry of harmful substances such as foreign antigens , toxins and microorganisms .
More recently, through loss-of-function and rescue-phenotype studies, RANKL is shown to be a receptor activator of NF-κB ligand and play a role in differentiation of M cells. RANKL is expressed throughout the small intestine, facilitates uptake of pathogens such as Salmonella, and is the most critical factor M cell differentiation. [5]
Like the other epithelial cell lineages in the small intestine, Paneth cells originate at the stem cell region near the bottom of the gland. [4] There are on average 5–12 Paneth cells in each small intestinal crypt. [5] Unlike the other epithelial cell types, Paneth cells migrate downward from the stem cell region and settle just adjacent to ...