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The destruction of microvilli can actually be beneficial sometimes, as in the case of elimination of microvilli on white blood cells which can be used to combat auto immune diseases. [6] Congenital lack of microvilli in the intestinal tract causes microvillus atrophy, a rare, usually fatal condition found in new-born babies.
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. [8]
Each of these microvilli are about 1 μm in length, around 1000 times shorter than a single villus. The intestinal villi are much smaller than any of the circular folds in the intestine. Villi increase the internal surface area of the intestinal walls making available a greater surface area for absorption.
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). In the small intestine, M cells are associated with Peyer's patches. Cup cells are a distinct cell type that produces vimentin. [13] Tuft cells play a part in the immune response. [13]
Other cellular extensions that protrude from the cell membrane are known as membrane protrusions or cell protrusions, also cell appendages, such as flagella, and microvilli. [ 8 ] [ 9 ] Microtentacles are cell protrusions attached to free-floating cells, associated with the spread of some cancer cells .
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 ...
Invasion of tumours through the layers of the gastrointestinal wall is used in staging of tumour spread. This affects treatment and prognosis. 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]
Diagram of the plant cell, with the cell wall in green. Cell walls serve similar purposes in those organisms that possess them. They may give cells rigidity and strength, offering protection against mechanical stress. The chemical composition and mechanical properties of the cell wall are linked with plant cell growth and morphogenesis. [11]