TRANSITIONAL EPITHELIUM

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More than one cell layers 
Number of cells layers change able depend on orgen 
The structure of the transitional epithelium is best studied in sections of the wall of the urinary bladder. It is to be noted that the microscopic structure of this special type of multilaminar epithelium varies greatly according to the state of distension of the urinary bladder.

Undistended (contracted) Transitional epi:
Transtional (contracted) 

 In the undistended (i.e, contracted) urinary bladder, the urothelium appears to consist of 6 or more layers of cells. The basal layer of the epithelium consists of cuboidal cells. Over the basal layer are present several layers of polygonal cells. The most superficial layer of the epithelium appears to consist of very large dome-shaped cells also called umbrella cells
whose highly convex apices bulge into the bladder cavity. Some of the umbrella cells contain two nuclei.

Distension (stretched) Transtional epi:
Transtional (distended) 
Distension of the urinary bladder stretches and flattens the epithelium. In the fully distended (i.e, stretched) state the transitional epithelium is seen to consist of only 2 or 3 layers. There is a basal layer of low cuboidal cells over which are present one or two layers of large flat (squamous) cells.

Found In :

  • Renal Pelvis 
  • Ureter
  • Blader 
  • Parts of male and female Urethra 

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