Final answer:
The urinary bladder is lined with transitional epithelial cells, which can stretch and become thinner as the bladder fills with urine, adapting to changes in volume.
Step-by-step explanation:
The lining of the urinary bladder is composed of transitional epithelial cells. These cells are specialized to accommodate the stretching and distending of the bladder as it fills with urine.
Transitional epithelial cells, also known as uroepithelial cells, are unique to the urinary system, and they are arranged in a stratified layer. When the bladder is empty, these cells appear to be piled up, giving the epithelial lining a thicker appearance. As the bladder fills and expands, the epithelial layer unfolds and becomes thinner.
This adaptability is critical for the function of the urinary bladder, as it must be able to hold varying volumes of urine. Other tissues such as the peritoneum also play a role in the structure of the bladder but do not line the interior. Thus, the correct answer to what lines the urinary bladder is transitional epithelial cells.