Definition of Congo red in English:

Congo red


  • A red-brown azo dye which becomes blue in acidic conditions, used as a chemical indicator and as a stain in histology.

    ‘The chemicals used in making Congo red and the other aniline dyes were primarily derived from the coal-tar waste products of the coal gas and steel industries in Germany's Ruhr Valley.’
    • ‘The presence of amyloid confirmed histologically by either Congo red or sulfonated Alcian blue stains or by electron microscopy was seen in 8 muscles.’
    • ‘Potassium permanganate incubation caused loss of reactivity with Congo red.’
    • ‘The term amyloid refers to proteinaceous, eosinophilic, amorphous material that when stained with Congo red produces a characteristic green birefringence under polarized light.’
    • ‘All eyes studied that had characteristics of amyloid accumulation by hematoxylin-eosin staining were also stained with Congo red.’


Congo red

/ˈkäNGɡō red/ /ˈkɑŋɡoʊ rɛd/