Ureter

Tubes used in the urinary system in most animals

The ureters are tubes composed of smooth muscle that transport urine from the kidneys to the urinary bladder. In adult humans, the ureters are typically 20–30 centimeters long and 3–4 millimeters in diameter. They are lined with urothelial cells, a form of transitional epithelium, and feature an extra layer of smooth muscle in the lower third to aid peristalsis.

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