A red-brown azo dye that becomes blue in acidic conditions, used as a chemical indicator and as a stain in histology.
- ‘Potassium permanganate incubation caused loss of reactivity with Congo red.’
- ‘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.’
- ‘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.’
We take a look at several popular, though confusing, punctuation marks.