THE HISTOCHEMICAL DEMONSTRATION OF HISTAMINE IN MAST CELLS

Abstract

The use of formaldehyde vapor fixation following freeze-drying of tissues permits the histochemical demonstration of histamine in rat mast cells by several color producing reactions and fluorescence. Formaldehyde vapor fixed, frozendried mast cells develop an orange color on reaction with diazotized p-bromoaniline; the cells reduce both ferric ferricyanide and methenamine silver, and fluoresce yellow-green in ultraviolet light. These reactions are consistent with the presence of a tetrahydropyridoiminazole formed in rat mast cells by the reaction of the contained histamine with the applied formaldehyde.