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Transitional Epithelium

Epithelium that stretches; found in bladder lining

Region-
SystemUrinary System
Transitional epithelium, also known as urothelium, is a specialized type of epithelium that can stretch and recoil without damage.[2] It consists of multiple layers of cells that change shape depending on the degree of distension in the organ it lines.

Anatomy

  • Structure:
    • In the relaxed state, the cells in the superficial layer appear dome-shaped (sometimes called "umbrella cells").[3]
    • When stretched, the cells flatten, resembling squamous cells.
  • Cell Layers:
    • Basal layer: Cuboidal cells.
    • Intermediate layer: Columnar or polygonal cells.[4]
    • Apical layer: Dome-shaped cells that flatten during stretching.[5]

Location

Transitional epithelium is found exclusively in the urinary system, where organs need to accommodate varying volumes of liquid. Major locations include:

Function

  • Stretchability: Allows organs to expand and contract without tearing.
  • Barrier: Provides a protective lining, preventing the leakage of urine and protecting underlying tissues from its toxic components.[7]

Clinical significance

  • Urinary Tract Infections (UTIs): Recurrent infections can damage the transitional epithelium, leading to discomfort and potential complications.
  • Bladder Cancer: Transitional cell carcinoma arises from the transitional epithelium and is a common cancer affecting the bladder.[8]
  • Obstruction Effects: Chronic obstruction (e.g., kidney stones) can cause changes in the transitional epithelium, potentially leading to complications like hydronephrosis.[1]

Published on January 10, 2025
Last updated on April 24, 2025
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