Where is transitional epithelium found, and what is its key property?

• A. It is found in the urinary bladder and can stretch.
• B. It lines the stomach and is rigid.
• C. It is found in the brain and is non-secreting.
• D. It lines the heart and is contractile.

Answer: (A)

Transitional epithelium is specialized to line organs that store urine and need to stretch as they fill. It forms the urothelium of the urinary tract, especially the urinary bladder, and its cells change shape from more cuboidal/columnar when the bladder is empty to flatter, squamous-like cells when stretched. This distensibility, combined with tight junctions that maintain a barrier, lets the bladder hold varying volumes of urine without leaking. That’s why the correct statement is that it’s found in the urinary bladder and can stretch. The other options don’t fit because stomach lining is a non-stretchy simple columnar epithelium, brain is lined by ependymal/other cells rather than transitional, and heart lining (endocardium) is not a contractile epithelial tissue.