What is a distinguishing feature of transitional epithelium?

Transitional epithelium is unique in its ability to contract and expand, which is essential for its role in the urinary system. This type of epithelium lines organs such as the bladder, ureters, and part of the urethra, allowing them to accommodate varying volumes of urine. When the bladder is empty, the transitional epithelial cells are more cuboidal in shape, and as the bladder fills, these cells stretch and flatten, transitioning to a more squamous shape. This characteristic structural adaption is key to the function of transitional epithelium, supporting the distensible nature of the organs it lines.

In contrast, other options present features that do not accurately describe transitional epithelium. For instance, the absence of a basement membrane does not apply, as all epithelial types, including transitional epithelium, rest on a basement membrane. Varied nucleus location is not specific to transitional epithelium, as multiple epithelial types can exhibit variability in nucleus position. Additionally, transitional epithelium is composed of more than one cell type, typically including both basal cells and umbrella cells, which further supports its functional diversity.