Which epithelial cell is the largest among those found in urine?

• A. Squamous epithelial cells
• B. Caudate epithelial cells
• C. Transitional epithelial cells
• D. Renal epithelial cells

Answer: (A)

Epithelial cells in urine vary in size depending on where they come from in the urinary tract. Squamous epithelial cells originate from the distal urethra and external genitalia and are large and flat on a smear. Transitional epithelial cells come from the renal pelvis, ureters, and bladder and are oval to round but smaller than squamous cells. Renal epithelial cells come from the tubules and are smaller still, often more cuboidal. Among these, the largest type seen in urine is squamous epithelial cells. Their big, flat shape makes them readily distinguishable, which is why they’re the correct answer. The other options are smaller, with transitional and renal cells being progressively smaller than squamous.