A natural dye derived from orcinol by treatment with air and ammonia, which as a purple dye complex is used in various histologic staining methods.
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or·ce·in 'ȯr-sē-ən n a purple nitrogenous dye that is the essential coloring matter of cudbear and archil and that is used as a biological stain
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or·ce·in (or-seґin) a brown coloring matter, derived from orcinol and soluble in alcohol; used as a specific stain for elastic tissue.Medical dictionary. 2011.