In Verhoeff-van Gieson staining, the most likely adjustment to improve differentiation between collagen and muscle is saturating which solution?

• A. Picric acid solution
• B. Hematoxylin solution
• C. Ethanol
• D. Water

Answer: (A)

In Verhoeff-van Gieson staining, collagen and muscle are differentiated mainly by the counterstain system: collagen picks up a yellow color from the picric acid component, while muscle takes up the red from acid fuchsin. The contrast between these two tissues depends on how strongly each one absorbs the counterstain. Saturating with a picric acid solution enhances the yellow staining of collagen, making it stand out more distinctly against the red-stained muscle. This selective intensification improves the contrast between collagen and muscle, which is exactly what you want when counting or identifying these tissues.

Using hematoxylin would emphasize nuclei and elastic fibers rather than collagen vs. muscle; saturating with ethanol or water does not selectively boost the yellow counterstain and thus won’t improve their differentiation.