Ureter

The ureter is a pair of muscular tubes that transport urine from the kidneys to the bladder. Each person typically has two ureters, one for each kidney. They are approximately 25 cm long and are composed of three main layers: an outer fibrous connective tissue layer, a middle smooth muscle layer responsible for peristalsis, and an inner mucosal lining made of transitional epithelium. Its primary function is to move urine from the renal pelvis in the kidney down to the urinary bladder. Peristaltic contractions in the smooth muscle layer propel urine efficiently regardless of body position. The ureter also contains sensory nerves that help regulate peristalsis based on stretch or presence of urine within its lumen. Ureter visualization is crucial during surgical procedures to avoid accidental injury. Modern intraoperative visualization relies increasingly on non-ionizing methods like NIR fluorescence for safety and precision.