Methylene blue can be used in the processing alcohols to dye tissues for identification when embedding.

• A. True
• B. False
• C. Only for visualization after sectioning
• D. Not used in processing

Answer: (A)

Dyeing tissue during processing to aid identification when embedding is a practical way to keep track of specimens and ensure correct orientation in the block. Methylene blue is a mild, soluble dye that can be added to processing alcohols so the tissue takes on a blue color. This visual cue helps you quickly recognize and distinguish the tissue in the paraffin block, which is especially helpful when handling multiple specimens or very small fragments. The dye is used in dilute form so it doesn’t meaningfully interfere with the final H&E staining, and any residual color is minimal by the time sections are prepared. So this practice is indeed used in processing to facilitate embedding.