DIFFERENCES IN THE RENAL PELVIC EPITHELIU M OF DOG AND CAT - HISTOLOGIC AND SCANNING ELECTRON-MICROSCOPIC FINDINGS AND THEIR POSSIBLE CLINICAL-SIGNIFICANCE

Epithelium from the renal pelvis of dogs and cats was investigated by light and scanning electron microscopy. Apart from regular transitiona l epithelium, a different type of epithelial lining was found in both species. Superficial cells in th is type of epithelium were smaller an d characterized by tightly packed, stub-shaped microvilli. Species-spe cific characteristics were found as to the localization of the two typ es of superficial cells: in the dog, most of the pelvic surface is cov ered by,,microvillar cells'', while regular transitional epithelium cl early prevails in the cat. In laboratory diagnosis an increased number of so-called ''renal epithelia'' in the urinary sediment is, therefor e, highly suggestive of renal inflammation in the cat, while it might only be a symptom of pyelitis in the dog. Due to their particular morp hology, these ''microvillar'' superficial cells might be responsible f or an exchange at substances between the urine in the renal pelvis and the renal parenchyma, as physiological studies have indicated.