THE HISTOCHEMICAL DEMONSTRATION OF INDOLE DERIVATIVES BY THE POST-COUPLED P-DIMETHYLAMINOBENZYLIDENE REACTION

Abstract

1. A highly specific, chromogenic, localizable and permanent histochemical method for the demonstration of indole derivatives by use of a post-coupled benzylidene reaction is described. 2. The mechanism of the reaction as well as its tissue specificity is discussed. 3. The localization of indole derivatives to such sites as the β-cells of the pituitary, the granules of blood and tissue eosinophiles, the granules of the Paneth cells in the small intestine, chief cell granules of the gastric fundus, zymogen granules of the pancreatic acinar cells, α-cells of the islets of Langerhans, fibrin, [See figures in the PDF file] fibers and cement substance of the lens, neurokeratin and thyroid colloid has been demonstrated. 4. The relationship between the known tryptophan content of proteins and the sites of a strongly positive benzylidene reaction is discussed as well as a similar correlation with sites of negative reaction. 5. There is a tryptamine-formaldehyde condensation product, that is not a tetrahydronorharman, and is benzylidene reactive. 6. The significance of the lack of staining of melanin and enterochromaffin substance by the post-coupled benzylidine reaction is discussed.