Iodine is the primary stain for which stain?

• A. Verhoeff, primary stain
• B. Masson trichrome
• C. Gomori trichrome
• D. Pyronin

Answer: (A)

In staining, the term “primary stain” refers to the dye that first binds to and colors the target structures before any differentiation or counterstaining. For elastic-fiber staining, the Verhoeff method uses an iodine-containing reagent as the main staining component, which forms a complex that binds strongly to elastic fibers and colors them dark (often black or very dark). The surrounding tissue is then counterstained to provide contrast. The other stains listed use different dye systems and do not rely on iodine as the primary staining component. So, iodine is most closely associated with the Verhoeff elastic-stain approach.