Ureter
• Lined by transitional epithelium and consists of mucosa,
muscularis, and adventitia
• Upper part lined by inner longitudinal and middle circular
smooth muscle layers
• Third longitudinal smooth muscle layer added in the lower
third of ureter
• Connective tissue adventitia surrounds the ureter

Bladder
• Thick muscular wall with three indistinct layers of smooth muscle
• Serosa lines superior surface and adventitia covers the inferior surface
• Transitional epithelium in empty bladder exhibits about six layers of cells
• When stretched, the transitional epithelium appears stratified squamous
• Changes in epithelium caused by thicker plasma membrane of superficial cells and plaques
• Plaques act like hinges, and allow cells to expand during stretching; cells become squamous
• Thicker plasma membrane and transitional epithelium provide osmotic barrier to urine