Renal tubular epithelial (RTE) cells line the renal tubules. Observation of RTE cells in the urine sediment is more significant than observation of other types of epithelial cells.
An RTE cell is distinguished by its eccentrically placed nucleus. The cells can be round, oval, columnar, or cuboidal. Papanicolaou stain is useful in distinguishing RTE cells from other mononuclear cells in urine. Two RTE cells are indicated by the arrows in the upper image.
Increased numbers of proximal and distal convoluted RTE cells are seen in cases of acute tubular necrosis and certain drug or heavy metal intoxication. Oval fat bodies are RTE cells that have absorbed lipids in the urinary filtrate. Their identity can be confirmed using polarized microscopy and lipid stains. An oval fat body is indicated by the arrow in the lower image.