[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Histology](https://durgical.com/en/histology/) › [Urinary system](https://durgical.com/en/histology/#a-urinary) › Ureter, bladder and urethra: urothelium [Histology](https://durgical.com/en/histology/) · [Urinary system](https://durgical.com/en/histology/#a-urinary) # Ureter, bladder and urethra: urothelium - Organ The urinary tract is lined by urothelium, an epithelium that stretches without tearing and seals the wall off from urine. Updated 2026-11-01 **See it in 3D:** [Ureters](https://durgical.com/en/anatomy/ureter/) · [Urinary bladder](https://durgical.com/en/anatomy/urinary-bladder/) · [Urethra (male)](https://durgical.com/en/anatomy/male-urethra/) ## Key points - Urothelium: several layers; the surface has large umbrella cells, sometimes binucleate, with uroplakin plaques that block urine. - Empty bladder: tall urothelium and folds (rugae); full bladder: thin epithelium with flattened cells. - Ureter: inner longitudinal and outer circular muscle, the reverse of the gut; a third outer longitudinal layer is added in the lower third. - Urethra: urothelium proximally, pseudostratified or stratified columnar in the middle, nonkeratinized stratified squamous near the meatus. - Urothelial carcinoma is the most common bladder cancer; smoking is its main risk factor and chronic schistosomiasis is linked to squamous carcinoma. ## What it is The ureter, bladder and proximal urethra are lined by urothelium (transitional epithelium). Its surface layer of umbrella cells forms a watertight barrier and changes shape as the bladder fills. The muscular wall moves urine by peristalsis and the bladder empties with the detrusor muscle. It is the origin of the most common bladder cancer, urothelial carcinoma. ## Structure - Ureter in cross section: star-shaped lumen from mucosal folds, urothelium, lamina propria, two or three muscle layers and adventitia. - Bladder: urothelium, lamina propria, a detrusor of interlacing smooth muscle bundles, and serosa only on the upper surface. - Trigone: smooth area of the bladder floor between the two ureteric openings and the urethral opening. ## Function - Carry urine from the renal pelvis to the bladder by peristaltic waves. - Store urine at low pressure and empty it by detrusor contraction. - Keep urine, which is hypertonic and may carry toxins, from being reabsorbed or harming the wall. ## Urinary tract: epithelium and key features | Segment | Epithelium | How to recognise it | | --- | --- | --- | | Ureter | Urothelium | Star-shaped lumen; inner longitudinal and outer circular muscle | | [Bladder](https://durgical.com/en/conditions/bladder-cancer/) | Urothelium with umbrella cells | Thick interlacing detrusor; folds when empty | | Female urethra | Urothelium proximally, nonkeratinized stratified squamous distally | Short, with periurethral mucous glands | | Male urethra | Urothelium in the prostatic part; pseudostratified or stratified columnar in the membranous and spongy parts; squamous in the navicular fossa | Mucous glands of Littré in the spongy part | ## Clinical notes - Urinary tract infection: most are caused by uropathogenic Escherichia coli, which sticks to urothelium with its fimbriae. - Stones lodge at the narrow points of the ureter (pelviureteric junction, crossing of the iliac vessels and ureterovesical junction). - Chronic cystitis or stones can cause squamous metaplasia of the urothelium. ## Memory aid Urothelium is an accordion with a lid: it folds and stretches, and its umbrella cells keep the urine out. ## Test yourself Think of the answer, then tap the question to see it. ## Which urothelial cells form the barrier against urine? The umbrella cells of the surface layer, with uroplakin plaques in their apical membrane. ## How are the muscle layers of the ureter arranged in its upper two thirds? Inner longitudinal and outer circular, the reverse of the gut wall. ## Which epithelium lines the urethra near the external meatus? Nonkeratinized stratified squamous epithelium. ## What is the most common histologic type of bladder cancer? Urothelial (transitional cell) carcinoma. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/histology/ureter-bladder-and-urethra-urothelium/) ## See it in 3D The structures of Durgical's 3D anatomy where it is found. - [Ureters](https://durgical.com/en/anatomy/ureter/) - [Urinary bladder](https://durgical.com/en/anatomy/urinary-bladder/) - [Urethra (male)](https://durgical.com/en/anatomy/male-urethra/) ## Related - [Simple, stratified, pseudostratified and transitional epithelium](https://durgical.com/en/histology/simple-stratified-pseudostratified-and-transitional-epithelium/) - [Kidney: cortex, medulla and the nephron](https://durgical.com/en/histology/kidney-cortex-medulla-and-the-nephron/) - [Smooth muscle](https://durgical.com/en/histology/smooth-muscle/) - [Epididymis, vas deferens, seminal glands and prostate](https://durgical.com/en/histology/epididymis-vas-deferens-seminal-glands-and-prostate/) ## Related conditions - [Bladder cancer](https://durgical.com/en/conditions/bladder-cancer/) - [Urinary tract infection (acute cystitis)](https://durgical.com/en/conditions/urinary-tract-infection/) - [Kidney stones (urolithiasis)](https://durgical.com/en/conditions/kidney-stones/) ## Microorganisms - [Escherichia coli](https://durgical.com/en/microbiology/escherichia-coli/) - [Schistosoma mansoni / S. haematobium / S. japonicum](https://durgical.com/en/microbiology/schistosoma-mansoni-s-haematobium-s-japonicum/) [← All of histology](https://durgical.com/en/histology/) Educational content on normal microscopic structure and its clinical relevance; no substitute for studying slides or for a health professional's advice. Sources: [25.2 Gross Anatomy of Urine Transport](https://openstax.org/books/anatomy-and-physiology-2e/pages/25-2-gross-anatomy-of-urine-transport) (OpenStax, Rice University, 2022); [Urinary Bladder](https://training.seer.cancer.gov/anatomy/urinary/components/bladder.html) (National Cancer Institute, SEER Training Modules, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/histology/ureter-bladder-and-urethra-urothelium/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/histology/ureter-bladder-and-urethra-urothelium/