Almost exclusively urinary bladder is lined by
**Core Concept**
The urinary bladder is lined by a specific type of epithelial tissue that plays a crucial role in maintaining its function and preventing damage. This type of epithelium is characterized by its ability to stretch and accommodate varying volumes of urine.
**Why the Correct Answer is Right**
The urinary bladder is lined by transitional epithelium, also known as urothelium. This unique epithelium is composed of multiple layers of epithelial cells that can stretch and contract to accommodate the varying volumes of urine. The cells in the basal layer of the transitional epithelium are columnar, while those in the suprabasal layers are flattened or cuboidal, allowing for the necessary elasticity and flexibility. The transitional epithelium also produces a glycoprotein called urothelial glycoprotein, which helps to prevent water and ions from passing through the bladder wall.
**Why Each Wrong Option is Incorrect**
* **Option A:** Squamous epithelium is not found in the urinary bladder, as it is typically associated with skin and mucous membranes that are exposed to the external environment.
* **Option B:** Cuboidal epithelium is found in some parts of the kidney, but it is not the primary type of epithelium lining the urinary bladder.
* **Option D:** Pseudostratified columnar epithelium is found in the respiratory and genitourinary tracts, but it is not characteristic of the urinary bladder.
**Clinical Pearl / High-Yield Fact**
The transitional epithelium of the urinary bladder is capable of stretching up to 10 times its normal size without losing its integrity, which is essential for maintaining continence and preventing damage to the bladder wall.
**Correct Answer: C. Transitional epithelium**