Facet cells (also known as capping cells) are a type of cell usually found in the transitional epithelium of the bladder. They specialize in function by having a modified plasma membrane which allows them to stretch and relax with ease. In addition to this they also feature tight junctions between the cells. This helps form an osmotic barrier which separates bodily fluids from hypertonic urine.
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Facet cells Wikipedia(Text) CC BY-SA