THE MECHANISM OF TISSUE STAINING BY FERRIC HYDROXYQUINOLINE METHODS FOR β-GLUCURONIDASE

Abstract

1. The investigations reported in this paper show that the staining product of the Fishman-Baker and other ferric hydroxyquinoline methods for the demonstration of β-glucuronidase is entirely uninfluenced by the presence or absence of the enzyme. 2. Staining is due to the uptake of ferric iron from the complex equilibrium mixture of the incubating medium. 3. The uptake of iron is influenced by a number of factors but is essentially dependent on the nature of the tissue. 4. Changes in the localization of iron staining which occur in tissues in physiological or pathological states are likely to be due to significant though ill-understood differences in affinity for iron shown by intracellular constituents.