Which staining method is associated with using formalin ammonium bromide as the preferred fixative?

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

Answer: (A)

The essential idea here is that different neuron-staining silver methods require specific fixatives to preserve delicate neural structures and optimize silver impregnation. The Cajal method uses formalin ammonium bromide as the preferred fixative because this fixative stabilizes the tissue in a way that preserves neurons and their processes and reduces nonspecific silver deposition. This compatibility with the fixative allows the silver to deposit selectively along neuronal cell bodies and dendrites, producing the crisp, detailed nerve cell outlines characteristic of the Cajal stain. Other silver methods rely on different fixatives, which can alter tissue preservation and background staining, making the formalin ammonium bromide fixative particular to the Cajal technique.