Transitional cells

Transitional epithelium

Transitional epithelium 1

Epith transitional

Transitional cells are a unique type of epithelial cell that line the urinary system, particularly the urinary bladder, the ureters, and parts of the urethra. These cells have the ability to stretch and return to their original state in response to varying volumes of urine, facilitating the storage and excretion processes.

Structure and Features

Transitional cells, or urothelial cells, are multilayered and possess the following characteristics:

• Surface Layer: The apical surface cells are large, dome-shaped, and often binucleated.
• Middle Layer: Contains smaller, irregularly shaped cells.
• Basal Layer: Comprises of cuboidal cells adjacent to the basement membrane.

One notable feature of transitional cells is their plasma membranes' ability to create a specialized and impermeable barrier. This prevents toxic substances present in urine from diffusing back into the bloodstream.

Function

The primary functions of transitional cells include:

• Distensibility: They can expand and contract to accommodate fluctuations in urine volume.
• Protection: They prevent urine components, especially harmful waste products, from diffusing into the bloodstream.

Disorders and Pathology

Transitional cells are the origin of several diseases, including:

• Transitional Cell Carcinoma (TCC): This is the most common type of bladder cancer and arises from the transitional cells lining the bladder. Risk factors include smoking, chronic bladder inflammation, and exposure to certain chemicals.
• Cystitis: An inflammation of the bladder lining, which can be caused by infections, chemicals, or other factors.

Diagnosis and Study

• Urine cytology tests are often utilized to examine the appearance of transitional cells, especially when looking for abnormal or cancerous cells.
• Biopsies of the urinary bladder can provide detailed insights into the state and health of the transitional cells.

See Also

• Epithelial cells
• Urinary system
• Transitional cell carcinoma
• Urothelium

References

• Wein, A.J., Kavoussi, L.R., & Novick, A.C. Campbell-Walsh Urology, 10th Edition. Saunders, 2011.
• Eble, J.N., Sauter, G., Epstein, J.I., & Sesterhenn, I.A. Pathology and Genetics of Tumours of the Urinary System and Male Genital Organs. IARC Press, 2004.

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