Transitional epithelium
Transitional epithelium of the urinary bladder. Note the rounded surface of the apical cells -- a distinguishing characteristic of this type of epithelium.
Transverse section of ureter.

Transitional epithelium (also known as urothelium) is a type of tissue consisting of multiple layers of epithelial cells which can contract and expand. These cells, part of the epithelium, are usually found in the urinary tract, especially around the urinary bladder. They are also found in the ureters, superior urethra and gland ducts of the prostate.

Contents 1 Appearance 2 Functions 3 Surfaces 4 See also 5 Additional images 6 External links

[edit] Appearance

These cells appear to be cuboidal when the organ or the tube in which they reside is not stretched. When the bladder fills, the tissue actually compresses and the cells become stretched, and they appear to be flat, irregular, and squamous.

[edit] Functions

The transitional epithelium cells accommodate fluctuation of volume of the liquid in an organ or tube, such as the urinary bladder, and protect against the caustic effects of urine.

[edit] Surfaces

The free surface of the tissue (the part that faces outward into the organ or tube) is called the apical surface or free surface.

The part that lines the bottom of the tissue is called the basement membrane.

[edit] See also

• Urotheliumand uterine

[edit] Additional images

Types of epithelium

Schematic view of transitional epithelium

Vertical section of bladder wall.

[edit] External links

• Histology at utmb.edu
• Histology at OU 36_02 - "ureter"
• Histology at OU 37_02 - "urinary bladder"
• Anatomy Atlases - Microscopic Anatomy, plate 02.24 - "Transitional Epithelium", Ureter
• Histology at KUMC urinary-renal16 "ureter"

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v • d • e Histology: epithelial tissue Types Columnar (simple, stratified) · Cuboidal (simple, stratified) · Pseudostratified (Respiratory) · Squamous (simple, stratified) · Transitional/Urothelium · Olfactory · Corneal Features Lateral/cell-cell Tight junction (Claudin, Occludin) · Adherens junction (Cadherin) · Desmosome (Desmoplakin, Plakoglobin, Tonofibril, Desmoglein) · Gap junction (Connexon, Connexin) Basal/cell-matrix Basal lamina · Hemidesmosome (Tonofibril) · Focal adhesion · Costamere Apical Cilia · Microvilli · Stereocilia