The distribution of ferritin has been studied in many tissues, but has not yet been established on the cellular level. We investigated the cellular distribution of ferritin in the liver, spleen and bone marrow using the immunoperoxidase method, and compared it with that of hemosiderin. We also examined changes in the distribution of these proteins after phlebotomy and iron overload. In normal rats, ferritin was seen in centrilobular hepatocytes, Kupffer cells, macrophages in the red and white pulp of the spleen and central macrophages in bone marrow. Hemosiderin was observed almost exclusively in the red pulp and partly in tangible body macrophages of the white pulp. After phlebotomy, neither ferritin nor hemosiderin were detectable in these cells except for ferritin-positive cells in the white pulp, which showed little change after either phlebotomy or iron overload. In iron overloaded rats, both ferritin and hemosiderin increased in hepatocytes and reticulo-endothelial (RE) cells. Ferritin-positive cells in the liver were mainly located in the periportal area. These results indicated that hepatocytes and RE cells except for those in the white pulp may play an important role in iron storage, and that ferritin-positive cells in the white pulp may have a function other than iron reserve. They also suggested that the zonal distribution of ferritin-positive hepatocytes may be due to microcirculation in the hepatic lobules.</p
