H01: The haematoxylin and eosin stain: from piracy to pathology

E. Butt¹ and I. Ashraf²

¹City Hospital, Birmingham, UK and ²Solihull Hospital, Solihull, UK

When the microscope was first invented by Zacharias Janssen in 1595, little was known about the intricate details of the skin and its diseases. Fresh tissue was cut by hand and examined unstained. It was almost 300 years later that the haematoxylin and eosin stain became established in histopathology. Haematoxylin originates from the natural logwood tree Haematoxylum campechianum, native to Central America and discovered by Spanish explorers of the Yucatán Peninsula in 1502. It was originally used as a clothing dye by Aztecs and Mayans, and later adopted by the Spanish, who enjoyed the transition of their garments from toneless rags to colourful fabrics. The new-found dye became an increasingly profitable source for Europe, meaning that Spanish ships harbouring the new logwood dye were lucrative targets for pirates and English attack. Spain even gained a monopoly over the dye, leading to increasing trading conflict culminating in the Seven Years’ War (1756–63) between the Spanish, French and English. In 1803, Thomas Andrew Knight (1759–1838), an eminent British botanist and horticulturalist, was the first to use the logwood dye to highlight vessels in plants. This translated into histology, when the founder of the Royal Microscopical Society, John Thomas Quekett (1815–1961), suggested using the haematoxylin stain on translucent material to aid visualization of structures under the microscope. Wilhelm von Waldeyer-Hartz (1836–1921) successfully dyed neuronal axons in the 1860s and discovered that this stain darkened material inside nuclei. He called this dark material ‘chromosome’ and consolidated the neuron theory with his newly discovered dye. The properties of haematoxylin further evolved in 1865, when aluminium was used as a mordant, allowing the dye to be made stronger and more stable. A more precise nuclear stain was developed by zoologist Paul Mayer (1848–1923) in 1891, by purifying haematoxylin into its active oxidized form, haematein. By 1876, eosin was used as the preferred acidic counterstain, establishing the foundations of today’s haematoxylin and eosin stain. An increasing variety of stains was developed by Paul Ehrlich (1854–1015), with the use of aniline dyes, allowing further diseases to be examined microscopically. The German father of dermatopathology, Paul Gerson Unna (1850–1929), examined the skin with these stains, and developed his own elastin ‘orcein’ stain. He authored his Histopathology of Skin Diseases in 1892, which – once translated in 1896 – became the first English book on dermatopathology. Today, the natural haematoxylin and eosin stain remains the most common and most versatile staining method used in dermatopathology.