True or False: methyl green-pyronin and toluidine blue are used to demo fibroblasts.

• A. True
• B. False
• C. Only MG-P
• D. Only Toluidine Blue

Answer: (B)

These stains don’t specifically highlight fibroblasts. Methyl green-pyronin differentiates DNA and RNA content in cells (DNA green, RNA red), so it’s useful for assessing cellular activity and identifying cells with high RNA synthesis, such as plasma cells, rather than defining fibroblasts. Toluidine blue stains acidic tissue components and shows metachromasia in tissues rich in sulfated proteoglycans (notably mast cell granules), making it helpful for identifying mast cells and certain matrix elements, but not for marking fibroblasts. To demonstrate fibroblasts, you’d rely on routine histology like H&E to see spindle-shaped cells within a collagenous matrix, or use connective tissue–specific stains (e.g., Masson’s trichrome) or mesenchymal markers (such as vimentin) in immunohistochemistry. So the statement is false.