Final answer:
Oval fat bodies are derived from renal tubular epithelium, indicating lipid accumulation in these cells, often due to renal pathology.
Step-by-step explanation:
Oval fat bodies are indeed of renal origin. Specifically, they are derived from renal tubular epithelium. Oval fat bodies refer to lipid-laden tubular epithelial cells that are often seen in urine samples and can be indicative of renal pathology, particularly when there is damage to the tubular cells leading to lipid accumulation. When stained with special dyes like Sudan III or IV, these lipids can show a characteristic "Maltese cross" appearance under polarized light microscopy. This is distinct from the cells of the transitional epithelium which lines the urinary tract and can change shape due to the pressure of urine, the degenerated white blood cells (WBCs) that may appear in urine due to infections or inflammation, and the mucoprotein matrix which would not constitute cellular entities like the oval fat bodies. In summary, the answer is A. Renal tubular epithelium.