In biomedical experiments nowadays, the hematoxylin-eosin stain is a common method to determine cell activity in biological research. It is simple and easy to operate. Staining method. So what is so special about hematoxylin-eosin staining among these staining methods?
What is hematoxylin?
Hematoxylin is a colorless or light grayish-yellow powder, which is not a dye in itself and is extracted from the heartwood of hematoxylin. It is oxidized to form hematoxylin, which combines with certain metal ions (mainly Fe(III) and Al(III)) to form colored complexes. It is used to stain cell nuclei and thus can be observed under a microscope.
Characteristics of hematoxylin
Hematoxylin can be used as a stain to differentiate different cell structures in various colors. The color of the tissues stained during differentiation varies depending on the treatment, from red after differentiation with acidic solutions (e.g., hydrochloric acid-alcohol), which revert to greenish-blue after washing, to blue after differentiation with alkaline solutions (e.g., ammonia), which turn blue-black after washing. It turns red when exposed to light.
Hematoxylin is also often used for hematoxylin-eosin staining (H&E), a method commonly used in histology to stain cell nuclei a deep purple color. The staining procedure is not complicated. The staining is permanent (whereas potassium iodide iodine solution staining is temporary). Although this strain is commonly referred to as heme, its active colorant is the oxidized form of heme, which forms intense colored complexes with certain metal ions, usually Fe(III) and Al(III) salts. In its pure form, heme is a colorless crystalline solid, but commercial samples are usually light to dark brown, depending on the degree of impurities present.
Extraction and purification of hematoxylin
Historically, excessive deforestation in Brazil and Central America caused a shortage of hematoxylin, and consequently, the price of hematoxylin skyrocketed, but no more suitable substitute was found. Extraction of hematoxylin is now carried out near where the logs are harvested. Water, ether, or alcohol are used as solvents, which allows the hematoxylin to reach experimental purity levels.
Uses of hematoxylin
Hematoxylin has been used as a stain for staining gastric cancer tissue, cardiac muscle tissue, heart sections, and ovarian cell nuclei.
We used hematoxylin provided by BenchChem for our experiments, mainly to stain cell nuclei so we could observe the different tissue structures in the cells. The principle of this experiment is that the hematoxylin dye is alkaline and stains the chromatin and nucleic acids in the cytoplasm of the nucleus (called the basophilic part) blue-purple. At the same time, eosin is an acidic dye that stains the eosinophilic part, such as the components of the extracellular matrix of the cytoplasmic nucleus, red. After treatment with hematoxylin staining, eosin was used to stain the cytoplasm, thus making the components appear in contrasting colors and leading to the desired experimental conclusion.
Because of the outstanding staining effect of hematoxylin and the speed and low cost of the experiment, hematoxylin-eosin staining is widely used in the staining of biological histology. After understanding hematoxylin as a stain, I hope you can better apply it to your experiments.