The centuries old stain: Hematoxylin and Eosin Y

When a pathologist tries to determine whether a biopsy is cancerous or not,  he/she is likely to be looking at a Hematoxylin and Eosin Y (H&E) stain of the biopsy. Very simply, Hematoxylin colors the nucleus of each cell and Eosin Y colors other parts of the cell for better visualization. Across the world, scientists use this dyeing process to look at different body parts with clarity. Unfortunately, its popularity in the medical community has obscured it’s rather interesting and entertaining past.

Long time ago, in the Maya civilization, there were these tall, hard trees with a blood red core. The Mayans loved this color, so they used the bark of the tree and dyed their clothes with it’s extract. When the Spaniards arrived, the Mayans were dressed in beautiful purple and dark red colored clothes. During the Spanish conquest however, all Mayan libraries were destroyed and so was the recipe of the dyeing process. The Spaniards did not think much about it, since even boiling the bark was enough to produce extracts that could color clothes. They were quick to realize the economic potential of this tree in the European textile market and started exporting them as logs. The English loved this logwood but couldn’t seize control of its supply from the Spaniards. By that time, the value of logwood has risen to a level where one cargo of logwood had more worth than a year’s worth of other cargoes. It was the major competition to indigo and woad dyeing industry in England, leading to major discontent among indigo and woad planters. There was another problem: logwood dye faded very quickly. Queen Elizabeth thought of a way to pacify the indigo planters’ discontent and also to deal Spain an economic blow  – an Act banning logwood use in England was passed. However, the skirmish with Spain over logwood continued until the sinking of Spanish Armada. Later, in the early 1600s, English logwood trade got a new boost when Cornelius Drebbel re-discovered the lost Mayan art of metal mordanting (where a metal helps the dye bind to the sample) that doesn’t let hematoxylin fade.

Around the same time polymath Robert Hooke first noticed that hematoxylin can also stain biological samples. It is bewildering why he didn’t try the mordant in his stains. But finally, two hundred years later, Frederic Bohmer published the first successful, long lasting stain with hematoxylin and alum as a mordant. In about the same time, Heinrich Caro synthesized a yellow-red dye  and named it Eosin after a girl he admired, “Eos”. A German scientist Wissowzky, then brought Eosin Y and hemoxylin together to have high contrast between different areas of the tissue.

You would imagine that for a technique steeped in 500 years history of blood, money and love – there will be a robust recipe available. But alas, Hematoxylin and Eosin Y likes to have people toil over them. So there I was, ransacking the internet about H&E stain for the last three months to get the contrast right. Finally, last week I worked out the correct conditions for a decently good stain of the mouse knee. I came back home, satisfied and put on some laundry. Guess what? My white jeans came out of the dryer a bright shade of pink. And thus continues the curse of the centuries old stain …

H&E stain of a mouse knee
My previously white jeans

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