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A crystalline compound, containing the coloring matter of Haematoxylon campechianum (logwood), from which it is obtained by extraction with ether. It is used as a dye in histology, especially for cell nuclei and chromosomes, muscle cross-striations, and enterochromaffin cells; its staining properties depend upon its oxidation to hematein and mordanting with chrome and iron alums. It is also used as an indicator (red to yellow at pH 0.0 to 1.0, yellow to violet at pH 5.0 to 6.0).

- Boehmer h. an alum type of h. in which natural ripening occurs in about 8 to 10 days, and the solution is good for many months.

- Delafield h. an alum type of h. used in histology; natural ripening takes about 2 months and the solution is good for years.

- Harris h. an alum type of h. similar to Delafield h., but which uses chemical ripening to produce oxidation of h. for immediate use.

- iron h. unique ferric lakes of hematein that produce deep blue-black stains; useful for studies of cytologic detail, such as chromosomes, spindle fibers, Golgi apparatus, myofibrils, and mitochrondria; also useful to demonstrate Entamoeba histolytica. SEE ALSO: Heidenhain iron h. stain, Weigert iron h. stain.

- phosphotungstic acid h. (PTAH) a stain with broad application in cytology and histology; nuclei, mitochrondria, fibrin, neuroglial fibrils, and cross-striations of skeletal and cardiac muscle stain blue; cartilage ground substance, bone reticulum, and elastin appear in shades of yellow-orange and brownish red; also useful for demonstrating abnormal or diseased astrocytes, often in combination with periodic acid -Schiff stain and Luxol fast blue. SYN: Mallory phosphotungstic acid h. stain.

he·ma·tox·y·lin or chiefly Brit hae·ma·tox·y·lin .hē-mə-'täk-sə-lən n a crystalline phenolic compound C₁₆H₁₄O₆ found in logwood and used chiefly as a biological stain because of its ready oxidation to hematein