Spinal cord is an excellent control for which technique?

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

Answer: (A)

Spinal cord is chosen as a control for Weil staining because it has a rich, orderly network of nerve fibers: dense white-matter tracts of axons and a well organized gray matter with neuronal processes. This makes the pattern produced by a valid Weil silver impregnation predictable and easy to evaluate. When the procedure is working, you should see clear, dark staining of fibers along the white-matter tracts and distinct staining of neuronal elements in the gray matter. If these features are weak, irregular, or absent, it signals a problem with the stain reagents, timing, or processing steps. The spinal cord’s consistent architecture provides a reliable, reproducible standard for this technique.