Which of the following characteristics distinguishes transitional epithelial cells?

Transitional epithelial cells are a unique type of cell found in the urinary tract, particularly lining the bladder, ureters, and parts of the urethra. One of their distinguishing characteristics is their size relative to other cell types. Transitional epithelial cells are typically larger than squamous cells, which are flat and thin. This larger size allows transitional cells to accommodate the stretching of the bladder as it fills with urine.

The other options do not accurately represent the characteristics of transitional epithelial cells. These cells are not exclusively spherical; they can change shape and size depending on the bladder's fullness. While they do originate from areas of the urinary tract like the bladder, they are also present in the ureters and parts of the urethra, making statement about localization misleading. Lastly, transitional epithelial cells have a distinct shape different from renal tubular cells, which are more cuboidal and involved in reabsorption and secretion functions in the nephron.