Hematoxylin

Hematoxylin is a basic dye that is widely used in histology for staining. It is a natural product extracted from the heartwood of the logwood tree (Haematoxylum campechianum). Hematoxylin is commonly used in combination with a counterstain, most frequently eosin, a process known as H&E staining, which is one of the most commonly used techniques in histopathology.

History

Hematoxylin was first used as a dye by Waldeyer in 1863. It was initially used in the textile industry, but its value in histology was soon recognized and it has been used in histological staining since the late 19th century.

Preparation and Use

Hematoxylin is usually used in the form of a solution, known as Harris hematoxylin, which is prepared by dissolving hematoxylin in alcohol and adding mercuric oxide and potassium iodate. This solution is then used to stain tissue sections, which are subsequently counterstained with eosin.

Hematoxylin stains nuclei blue to black, due to its affinity for nuclear substances such as DNA and RNA. The counterstain, eosin, stains the cytoplasm and extracellular matrix pink to red.

Applications

Hematoxylin is used in a variety of histological staining techniques, including H&E staining, Papanicolaou stain, and Van Gieson's stain. It is also used in the Feulgen stain for DNA and the PAS stain for glycogen and mucin.

Safety and Environmental Concerns

Hematoxylin is generally considered safe to use in the laboratory. However, it can cause skin and eye irritation, and should be handled with care. The logwood tree from which hematoxylin is extracted is not endangered, but overharvesting can lead to local extinction.

See Also

• Eosin
• Histology
• H&E staining
• Papanicolaou stain
• Van Gieson's stain
• Feulgen stain
• PAS stain

Hematoxylin Resources
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