Elastic fibers are a form of connective tissue fibers that are highly refractive. Elastic fibers are known to stain with acid dyes and are also intensely stained by the Verhoff-Van Gieson staining method. The Verhoeff-Van Gieson (VVG) staining method relies on ferric chloride and iodine that act as a mordant (linking hematoxylin dye molecules to tissue components) while also acting as an oxidizer that converts hematoxylin to hematein. This solution is used to overstain the tissue section.
Subsequent differentiation of the overstained tissue section follows and is carried out using excess mordant (ferric chloride). Exposure of the tissue section to the ferric chloride breaks the tissue-mordant-dye complex as the dye is attracted to the more significant amount of mordant. Since the elastic fibers have a stronger affinity for the iron-hematoxylin complex than any other tissue components, they retain the dye through differentiation. An application of sodium thiosulfate removes any excess iodine.
A final step of counterstaining with Van Gieson's solution provides contrast for the stained elastic fibers against other decolorized tissue elements.
