Staining of minerals and solubility of iron in tissues

Iron deposits in ethionine induced aortic siderosis of rats, in splenic deposits in sickle cell anemia and siderocalcific vessels in cerebral arteriosclerosis were completely removed by exposure to 20 percent hydrochloric acid for 30 min. This contrasted with idiopathic hemochromatosis and idiopathic pulmonary hemosiderosis in which the iron containing organs had to be exposed to 40 percent hydrochloric acid for two hours. The more soluble iron appeared colorless in unstained tissues, purplish blue with hematoxylin and eosin, turquoise blue with Perls' stain, violet blue with gallocyanin and dark-drown with sodium rhodizonate. The less soluble iron was golden yellow in unstained tissues. It appeared golden yellow with hematoxylin and eosin and sodium rhodizonate, but it stained greenish blue with Perls' method and dark brown with gallocyanin. Lead and copper were capable of deposition in some tissues in vitro in the presence of iron and/or calcium but not when these minerals were removed. This phenomenon may be of importance in certain pathological conditions, e.g. hemochromatosis, where on preexisting tissue-iron-complexes there is a secondary deposition of copper.