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A pigment precursor.
A microorganism capable of producing color under suitable conditions.



according to the color theory devised by O. Witt, a substance containing chromophores—groups of atoms responsible for the coloration of various compounds. The term was also used to designate colorless substances found in animal and plant tissues that become pigments as a result of oxidation. V. I. Palladin proposed the term “respiratory chromogen” as part of his theory of plant respiration in reference to substances that become pigments through reversible oxidation. The equivalent Russian term is no longer used in the literature.

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The complex is then visualized with a hydrogen peroxide substrate and 3, 3'-diaminobenzidine tetrahydrochloride (DAB) chromogen, which produces a dark brown precipitate, readily detected by light microscopy.
The intelliPATH FLX is a fully open, random-access immunohistochemistry staining instrument, that has STAT capability with priority processing, rapid four-step multistaining and on-board preparation of chromogens and reagents.
No reliable transformation of creatinine values obtained with the enzyme-based procedures into values produced by modified Jaffe procedures is known because modified Jaffe procedures determine pseudocreatinine chromogens in addition to creatinine and because the amounts of pseudo-creatinine chromogens vary among samples.
ABSTRACT Most marine snails of the families Muricidae and Thaididae produce in their hypobranchial gland (mucus gland) a colorless secretion containing minute amounts of chromogens, which develop under the influence of light and oxygen into a pigment known as "Tyrian Purple.
Signet offers negative controls, chromogens, antibody diluents, epitope retrieval buffers, wash buffers for use in manual and automated staining, blocking reagents and enhancers to help your laboratory achieve excellence in immunostaining.
The secretion contains, besides mucus and biologically active compounds, minute amounts of chromogens, which develop enzymatically and under the influence of light and oxygen into a purple pigment known as "Tyrian purple," "Royal purple," or "Shellfish purple.
Other changes include a darkening of the urine color, due to oxidation of colorless chromogens such as the oxidation of urobilinogen to urobilin, or a change in color as bilirubin is oxidized to biliverdin.
By using 2 chromogens, methyl green, which stains all nuclei, and diaminobenzidine, which stains only the nuclei that express PCNA, a percent p53 nuclear staining area and proliferation index were calculated.
We compared the results obtained with the two chromogens on 66 liver biopsies from patients with chronic liver diseases hospitalized in the Department of Hepatogastroenterology of the Pitie-Salpetriere Hospital.
Substrate chromogens were incubated for ~10 minutes.
Peroxidase systems generally use 3,3'-diaminobenzidine (DAB) (brown) or 3-amino-9-ethylcarbazole (AEC) (red) chromogens.