Weigert's stain

Weigert's stain is a histochemical staining method used predominantly in the fields of histology and neuroscience to visualise myelin, a fatty insulating sheath that covers the axons of many neurons and plays a crucial role in speeding up neural conduction. This stain specifically targets myelin, providing a stark contrast that allows researchers to observe its presence and distribution within a given sample of nervous tissue.

Developed by German pathologist Karl Weigert, Weigert's stain uses aniline and other chemicals to provide a colour reaction. The technique works by staining myelin sheaths black, while other cellular components generally take on lighter colours, often counterstained with eosin to produce a pink or red colour. The resultant contrast is ideal for distinguishing myelinated from non-myelinated structures.

There are a few variations of Weigert's stain, but these are most commonly used:

Weigert's iron hematoxylin staining

This is used to stain myelin and nuclei. Hematoxylin, in combination with iron salts (ferric chloride), forms an iron-hematoxylin complex that binds selectively to myelin, producing a deep blue or black color.

Weigert's Van Gieson stain

This is a combination of Weigert's Iron Hematoxylin and Van Gieson's stain used primarily for the differential staining of collagen fibres, muscle, and nuclei in histological sections. Hematoxylin serves as the primary stain and, when combined with iron salts (like ferric chloride), creates an iron-hematoxylin complex that specifically binds to nuclei. Van Gieson's stain is a mixture of Picric acid and Acid Fuchsin. Picric acid stains collagen fibres yellow or yellowish-brown. Acid Fuchsin, being a basic dye, stains cytoplasm and muscle fibres red.

Weigert's Resorcin-Fuchsin Stain

This is used for staining elastic fibers in tissues. After pretreating with oxidizing agents like potassium permanganate or chromic acid, sections are stained with Weigert's iron hematoxylin followed by resorcin-fuchsin solution, which specifically stains elastic fibers.

Luxol Fast Blue with Weigert's Hematoxylin (for Myelin)

Luxol fast blue is a commonly used stain for myelin. Weigert's hematoxylin can be used in combination with it to provide contrast by staining the nuclei black.

p.s. see a tremendous example of Luxol Fast Blue on its own here

These are just a few examples of the various staining combinations involving Weigert's hematoxylin. The choice of counterstain or combination usually depends on the specific tissue components one wishes to visualize. Combining Weigert's hematoxylin with other stains provides clear, contrasting colours that enhance the interpretability of histological sections. For example, the combination of Weigert's Iron Hematoxylin and Van Gieson provides a clear contrast between nuclei (black), collagen fibres (yellow), and muscle (red), making it an excellent tool for studies in connective tissue

The staining method has a number of applications. Because it provides a detailed look at the distribution and organisation of myelinated fibres, it's an invaluable tool in both research and clinical settings. It can aid in the study of myelin-related diseases, such as multiple sclerosis, where the myelin sheath gets progressively damaged. Additionally, it can be utilised to visualise the microstructure of the brain and spinal cord in post-mortem studies, contributing to our understanding of neuroanatomy.