The ureters are tubes continuous with the renal pelvis, which transport urine from the kidneys by peristalsis.

• Examine images below and these slides of ureter (sample 1, sample 2), noting the folded mucosa surrounded by two layers of smooth muscle and adventitia. In the folds of the urinary epithelium (or urothelium) note the umbrella shaped surface cells and the thin basement membrane with closely associated capillaries.

The bladder collects urine from the ureters for storage and drainage via the urethra.

• Examine the image below and trichrome-stained and an H&E stained sections  of bladder. Observe the urinary or transitional epithelium that is specialized to withstand the hypertonic urine and to distend when the bladder is full. Identify the lamina propria, submucosa, muscularis with three layers of smooth muscle (detrusor muscle), and outer serosa/adventitia. The outer layer may contain Pacinian corpuscles, which sense pressure within the bladder.

Clinical note: Transitional cell carcinoma, the most common type of bladder cancer, is associated with occupational exposure to certain organic chemicals among workers in the dye, rubber, paint, and some other industries. Smokers also have a four-fold increased risk for bladder cancer compared to nonsmokers.

Almost there, last comes the urethra.