[1] This tissue consists of multiple layers of epithelial cells which can contract and expand in order to adapt to the degree of distension needed.

Transitional epithelium is made up of three types of cell layers: basal, intermediate, and superficial.

[3] The basal layer fosters the epithelial stem cells in order to provide constant renewal of the epithelium.

[6] Because of its importance in acting as an osmotic barrier between the contents of the urinary tract and the surrounding organs and tissues, transitional epithelium is relatively impermeable to water and salts.

[7] The membrane is made up of a hexagonal lattice put together in the Golgi apparatus and implanted into the surface of the cell by reverse pinocytosis, a type of exocytosis.

[8] The cells in the superficial layer of the transitional epithelium are highly differentiated, allowing for maintenance of this barrier membrane.

[5] The transitional epithelium cells stretch readily in order to accommodate fluctuation of volume of the liquid in an organ (the distal part of the urethra becomes non-keratinized stratified squamous epithelium in females; the part that lines the bottom of the tissue is called the basement membrane).

Transitional epithelium also functions as a barrier between the lumen, or inside hollow space of the tract that it lines and the bloodstream.

Aristolochic acid, a compound found in plants of the family Aristolochiaceae, also causes DNA mutations and is a cause of liver, urothelial and bladder cancers.

Transitional cell carcinoma can metastasize, or spread to other parts of the body via the surrounding tissues, the lymph system, and the bloodstream.

Common risk factors of transitional cell carcinoma include long-term misuse of pain medication, smoking, and exposure to chemicals used in the making of leather, plastic, textiles, and rubber.

However, while this method is effective in improving the function of the bladder, it can actually increases the risk of cancer, and can cause other complications, such as infections, urinary stones, and electrolyte imbalance.

For example, current research paves the way for use of pluripotent stem cells to derive urothelium, as they are highly and indefinitely proliferative in vitro (i.e. outside of the body).

Since the purpose of the urothelium is to act as a highly resistant barrier, the loss of this function has serious clinical implications.