Umbrella cell

Umbrella cells (also known as facet cells, capping cells, and superficial urotheliocytes) are a type of cells located in the bladder, the renal pelvis, the ureters, and the urethra. Umbrella cells form the outermost layer of the urothelium of these organs. Umbrella cells are special in that they can contain multiple nuclei. Their apical membrane contains numerous invaginations, which allows the cells to stretch during urination. Umbrella cells are linked together with tight junctions which:

prevents urine from leaking through the epithelium.
creates an osmotic barrier: urine osmotic concentration can range from 50 to 1200 mmol/L while the normal concentration is 290 mmol/L. The difference between the two could lead to fluid entering or exiting the ureter due to the osmotic pressure.

Umbrella cells contain the proteins uroplakin-1a uroplakin-1b, uroplakin-2, and uroplakin-3a. These increase the strength of the urothelium.

References

↑ Born, Martin; Pahner, Ingrid; Ahnert-Hilger, Gudrun; Jöns, Thomas (July 2003). "The maintenance of the permeability barrier of bladder facet cells requires a continuous fusion of discoid vesicles with the apical plasma membrane". European Journal of Cell Biology. 82 (7): 343–350. doi:10.1078/0171-9335-00326. PMID 12924629.
↑ Hickling, DR; Sun, TT; Wu, XR (August 2015). "Anatomy and Physiology of the Urinary Tract: Relation to Host Defense and Microbial Infection". Microbiology spectrum. 3 (4). doi:10.1128/microbiolspec.UTI-0016-2012. PMC 4566164. PMID 26350322.
↑ Lüllman-Rauch (2008). Histologie 1er cycle des études médicales. De Boeck Supérieur. ISBN 9782804156923.
↑ Riedel, Ina; Liang, Feng-Xia; Deng, Fang-Ming; Tu, Liyu; Kreibich, Gert; Wu, Xue-Ru; Sun, Tung-Tien; Hergt, Michaela; Moll, Roland (2005-03-09). "Urothelial umbrella cells of human ureter are heterogeneous with respect to their uroplakin composition: different degrees of urothelial maturity in ureter and bladder?". European Journal of Cell Biology. 84 (2–3): 393–405. doi:10.1016/j.ejcb.2004.12.011. ISSN 0171-9335. PMID 15819416.

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[1] Born, Martin; Pahner, Ingrid; Ahnert-Hilger, Gudrun; Jöns, Thomas (July 2003). "The maintenance of the permeability barrier of bladder facet cells requires a continuous fusion of discoid vesicles with the apical plasma membrane". European Journal of Cell Biology. 82 (7): 343–350. doi:10.1078/0171-9335-00326. PMID 12924629.

[Hickling2015-2] Hickling, DR; Sun, TT; Wu, XR (August 2015). "Anatomy and Physiology of the Urinary Tract: Relation to Host Defense and Microbial Infection". Microbiology spectrum. 3 (4). doi:10.1128/microbiolspec.UTI-0016-2012. PMC 4566164. PMID 26350322.

[hist-3] Lüllman-Rauch (2008). Histologie 1er cycle des études médicales. De Boeck Supérieur. ISBN 9782804156923.

[Reidel-4] Riedel, Ina; Liang, Feng-Xia; Deng, Fang-Ming; Tu, Liyu; Kreibich, Gert; Wu, Xue-Ru; Sun, Tung-Tien; Hergt, Michaela; Moll, Roland (2005-03-09). "Urothelial umbrella cells of human ureter are heterogeneous with respect to their uroplakin composition: different degrees of urothelial maturity in ureter and bladder?". European Journal of Cell Biology. 84 (2–3): 393–405. doi:10.1016/j.ejcb.2004.12.011. ISSN 0171-9335. PMID 15819416.