A colorless background indicates a problem with the cresyl echt violet stain.

• A. True
• B. False
• C. Sometimes true
• D. It depends on tissue type

Answer: (B)

Cresyl echt violet staining highlights neuronal cell bodies by coloring the Nissl substance (rough endoplasmic reticulum) a dark blue‑purple, while the surrounding tissue background remains light. The key for interpreting these slides is the presence and definition of the Nissl bodies within neurons, not how vividly the background itself is stained. A colorless background is not a reliable indicator of a problem with the cresyl echt violet stain because background color can be influenced by various processing steps that occur before, during, or after staining (hydration, differentiation, clearing, mounting). If the Nissl bodies are well defined and intensely stained, the slide can be acceptable even if the background is very pale or colorless. Conversely, issues in other steps could produce a pale background without reflecting a failure of the cresyl violet stain itself.