[Ultrastructural characteristics of renal cancer cells].

The ultrastructural study of the renal carcinoma revealed some differences in the fine structure of the two main cell types: clear and dark cells. The cytoplasm of clear cells is rich in fat and glycogen. Fat is found in lipid vacuoles and glycogen in diffuse granularity in the cell cytoplasm. Dark cells contain small amounts of fat and glycogen but have well developed mitochondria and other organelles. Comparison of these cell types shows some features of their similarity such as microvilli on the cell surface, desmosomes and interdigitations in the region of cell contacts and channels between tumour cells. These features suggest that clear and dark cells have a common origin from the epithelium of the proximal tubules.