All histotechnologists know that H&E, Hematoxylin & Eosin, is the gold standard of stains. It is essential, so the idea of an alternative to hematoxylin is unfathomable to many. It is true that no one thing could replace hematoxylin in all its uses, but if hard pressed, there are alternatives that can be used in some situations. Hematoxylin is a nuclear stain, so suggested alternatives are most often other nuclear stains such as nuclear fast red. The most commonly used substitute is celestine blue, but these alternatives rarely give the nuclear clarity that hematoxylin does.
Hematoxylin is one of 6 natural dyes commonly used in histology. Natural dyes come from sources occurring in nature, and are the contrast to synthetic dyes, which are made in a lab. There are some natural dyes, such as indigo that are naturally occurring, but can also be made synthetically. Hematoxylin is not one of those cases. It is made from the bark of logwood trees and can only be made naturally. The hematoxylin that is extracted from the tree is then oxidized into hematein, which is what we use as the stain. This is part of the reason why hematoxylin is unique. You can substitute other synthetically made blue nuclei dyes, but they are not going to produce the same results as hematoxylin.
The fact that it is made from a natural source, tree bark, is also what makes it subject to a potential shortage. Clearing forests to make way for production of other industries could mean reduced supply of the trees needed for hematoxylin production. In fact, there have been periods in histology’s history in which hematoxylin shortages have been referenced. This article from Sakura’s 2009 Histologic bulletin, in which they test several hematoxylin substitutes, discusses 2008 rumors about a hematoxylin shortage, and references another period in the 1970’s in which celestine blue was frequently used as a hematoxylin alternative.
So, while hematoxylin alternatives may not be immediately necessary or ideal, it is still worthwhile to consider the alternatives, in case environmental or cultural factors dramatically reduce our access to the precious logwood tree.
References:
https://www.tandfonline.com/doi/abs/10.3109/10520290903048400?fbclid=IwAR3J__CmvoldwVqOsgR1h6pxu2H8VAmgnwfqWLO-ci3p1bp41vxWXcPFHMo&journalCode=ibih20
https://www.tandfonline.com/doi/abs/10.3109/10520297609116665?fbclid=IwAR1--d3AK4DT450UFuCT7-F7-xCbJvM90ylaUBn5RG1bSJ_tgfn0ZvjjTaY
http://www.ihcworld.com/_histologic/pdf/09_jun.pdf