The stain most likely used in the image is?

• A. Cajal
• B. Nissl
• C. Hematoxylin
• D. PAS

Answer: (A)

The appearance is characteristic of a stain that reveals entire neuron shapes, including long dendritic and axonal processes, in a dark, detailed silhouette. This is achieved by the silver impregnation method developed for neurons, often called Golgi-Cajal staining. It selectively impregnates a small subset of neurons, painting their soma and all their processes in a dark color, which makes the full morphology stand out against a light background. That’s why you see long, branching processes radiating from the cell body.

Nissl staining would highlight only the cell body’s rough endoplasmic reticulum as granular blue-purplish cytoplasm, not the fine processes. Hematoxylin stains nuclei, not complete neuronal processes. PAS highlights carbohydrates in specific structures like glycogen and basement membranes, not neuron morphology. So the feature that best matches the image is the Golgi-Cajal (Cajal) silver impregnation staining.