Iron-Hematoxylin Staining


Iron-hematoxylin staining is a traditional staining technique that is commonly used for the detection of intestinal protozoans, such as amoebae, ciliates and flagellates. It is especially useful for demonstrating the nuclear structures of these parasites, which are important for their identification and differentiation. Iron-hematoxylin staining was the stain used for most of the original morphological descriptions of intestinal protozoa found in humans .

Iron-hematoxylin staining is based on the formation of a complex between hematein, a derivative of hematoxylin, and iron salts, which acts as a mordant. The iron-hematoxylin complex is a basic dye that stains the nuclei and other acidic structures of the parasites dark purple to black, while the cytoplasm remains lightly stained or unstained. The contrast between the nuclear and cytoplasmic staining allows for easy observation and quantification of the protozoan morphology under a light microscope.

Iron-hematoxylin staining can be applied to fresh, PVA-preserved or SAF-preserved stool specimens. PVA (polyvinyl alcohol) and SAF (sodium acetate-acetic acid-formalin) are two common fixatives that are used to preserve stool specimens for parasitological examination. The advantage of using preserved specimens is that they can be stored for a longer time and transported without refrigeration. However, some modifications in the staining procedure are required for PVA-preserved and SAF-preserved specimens, such as using iodine-alcohol to remove the fixative and adding Mayer`s albumin to improve the adherence of the smear to the slide.

Iron-hematoxylin staining is a relatively simple and inexpensive technique that can be performed manually or automatically. However, it requires careful attention to the quality and preparation of the reagents, the fixation and dehydration of the specimens, and the timing and washing of the staining steps. If these factors are not controlled properly, the staining results may be distorted or inconsistent.

Iron-hematoxylin staining is one of the most widely used stains in parasitology because it provides permanent slides that can be stored and reviewed for reference. It also offers high clarity and specificity for the differentiation of intestinal protozoans, which may not be achieved by other stains such as trichrome or iodine. However, iron-hematoxylin staining also has some limitations, such as being slow and time-consuming, requiring hazardous chemicals such as mercuric chloride and xylene, and being unable to distinguish some species or genera of protozoans that have similar nuclear structures.

In this article, we will explain the principle behind iron-hematoxylin staining, describe the objectives and reagents used in this technique, outline the procedure of iron-hematoxylin staining for different types of specimens, discuss the result and interpretation of iron-hematoxylin staining, and highlight the applications, advantages and limitations of this technique. We hope that this article will help you understand and perform iron-hematoxylin staining more effectively and confidently in your laboratory practice.