n. a colourless crystalline compound extracted from logwood (Haematoxylon campechianum) and used in various histological stains. When oxidized haematoxylin is converted to haematein, which imparts a blue colour to certain parts of cells, especially cell nuclei. Heidenhain’s iron haematoxylin is used to stain sections that are to be photographed, since it gives great clarity at high magnification.
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