Hematoksilina

Hematoxylin is a natural dye commonly used in histology and microscopy. It is derived from the heartwood of several species of trees, most notably the logwood tree (Haematoxylum campechianum). In its raw form, hematoxylin is a colorless compound called hematoxylin. It must be oxidized to form hematein, which is the actual colored dye. This oxidation process can be achieved through various methods, often involving exposure to air or specific oxidizing agents.

Hematoxylin is most frequently used in combination with a counterstain, typically eosin, in a staining technique known as Hematoxylin and Eosin (H&E) staining. This is one of the most widely used staining methods in biological research and medical diagnostics, particularly in the examination of tissue samples. Hematoxylin stains the nuclei of cells a blue or purple color. It achieves this by binding to the acidic components within the nucleus, primarily the deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), which carry a negative charge.

The precise mechanism of hematoxylin staining involves the use of a mordant, which is a substance that helps the dye bind to the tissue. Common mordants include aluminum salts, such as aluminum sulfate or aluminum potassium sulfate (alum). The mordant forms a complex with the hematein, which then readily binds to the negatively charged nucleic acids in the cell nucleus. The intensity and specific hue of the stain can be influenced by the type of mordant used, the pH of the staining solution, and the duration of staining. Hematoxylin staining is a crucial step in visualizing cellular structures and identifying pathological changes in tissues.