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Goblet cells are simple columnar epithelial cells, having a height of four times that of their width. The cytoplasm of goblet cells tends to be displaced toward the basal end of the cell body by the large mucin granules, which accumulate near the apical surface of the cell along the Golgi apparatus, which lies between the granules and the nucleus.
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.
Cells that absorb substances need a large surface area in contact with the substance to be efficient. [ 7 ] In intestinal cells, the microvilli are referred to as brush border and are protoplasmic extensions contrary to villi which are submucosal folds, while in the kidneys, microvilli are referred to as striated border.
Goblet cells secrete the mucus layer which protects the epithelium from the luminal contents. Enteroendocrine cells secrete various gastrointestinal hormones including secretin, pancreozymin, enteroglucagon among others. Subsets of sensory intestinal epithelial cells synapse with nerves, [9] and are known as neuropod cells. [10]
The nuclei of the cells (located at the outer edges of the cells lining the walls of the crypts) are stained blue-gray with haematoxylin. As seen in panels C and D, crypts are about 75 to about 110 cells long. The average crypt circumference is 23 cells. [8] From the images, an average is shown to be about 1,725 to 2530 cells per colonic crypt.
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.
Thousands of microvilli form a structure called the brush border that is found on the apical surface of some epithelial cells, such as the small intestines. (Microvilli should not be confused with intestinal villi, which are made of many cells. Each of these cells has many microvilli.)
Intestinal stem cell aging has been studied in Drosophila as a model for understanding the biology of stem cell/niche aging. [4] Using knockdown mutants defective in various genes that function in the DNA damage response in enterocytes, it was shown that deficiency in the DNA damage response accelerates intestinal stem cell aging, thus ...