Which stain is a silver impregnation method and is used to demonstrate nerve fibers?

• A. Holmes
• B. Cajal
• C. Bodian
• D. Bielschowsky

Answer: (A)

Silver impregnation methods reveal nerve fibers by depositing silver along the fiber structures, making them stand out as dark lines against a lighter background. The Holmes stain is a classic example of this approach and is specifically used to demonstrate nerve fibers, particularly myelinated fibers, by impregnating the tissue with silver so the fibers become dark and easily visible. This gives sharp contrast and allows clear visualization of the nerve fiber network in a section. Other silver-based stains like Bodian or Bielschowsky also highlight neural elements such as axons or neurofibrils, but the Holmes stain is the one most traditionally associated with directly demonstrating nerve fibers themselves. The Cajal method, while also using silver, is focused more on outlining neuronal components in a different context.