Mesangial cells of the lamprey, Lampetra japonica, store vitamin A.

Structure and vitamin A-storage of the mesangial cells in the lamprey kidney are documented using the gold chloride method, fluorescence histochemistry and electron microscopy. Abundant lipid droplets in the cytoplasm of the mesangial cells release intense, but quickly fading vitamin A-fluorescence under a fluorescence microscope and react with gold chloride. Characteristic tubular invaginations of the plasma membrane which usually occur in the lamprey smooth muscle cells are observed in these cells. We discuss similarities of the lamprey mesangial cells with hepatic stellate cells in the lamprey and mammals, such as vitamin A-storage, blood flow-regulation and proliferative potential. To the best of our knowledge, this is the first report on and proof of vitamin A-storage in mesangial cells, providing evidence for a vitamin A-storing cell lineage in vertebrates.