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 · Urinary bladder · Urethra (male)
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 | 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.
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.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- Simple, stratified, pseudostratified and transitional epithelium
- Kidney: cortex, medulla and the nephron
- Smooth muscle
- Epididymis, vas deferens, seminal glands and prostate
Related conditions
Microorganisms
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 (OpenStax, Rice University, 2022); Urinary Bladder (National Cancer Institute, SEER Training Modules, 2026).
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Representative model, for educational purposes only.