Ethylene glycol functions in Gill hematoxylin solutions to do which of the following?

• A. Prevent surface sheen
• B. Act as a mordant
• C. Stabilize pH
• D. Increase viscosity

Answer: (A)

Ethylene glycol acts as a humectant in Gill hematoxylin solutions. By retaining moisture around the tissue surface, it slows evaporation during staining, which helps keep the surface from drying and developing a glossy, reflective “surface sheen.” This moisture helps the hematein-aluminum mordant complex penetrate and bind more evenly to nuclear chromatin, producing a uniform blue-black nuclear stain. It isn’t functioning as the mordant, a pH stabilizer, or a viscosity modifier—the primary role here is maintaining a consistently moist environment to prevent surface sheen.