Ultrastructure of the interstitial cells of the renal papilla in the white rat

Interstitial cells of the renal papilla have the phenotypic appearance, being more of a fibroblast than of a histiocyte character. Interstitial cells differ from the "typical fibroblasts" in the number of lipid droplets, in the development of cisternae of the Golgi complex and rough endoplasmic reticulum, and in the number of lysosome-like bodies and mitochondria.