Toluidine Blue is an alkaline quinonimine dye (vivo dye) with high affinity for acidic tissue components, staining nuclei blue and polysaccharides purple. This dye shows heterostaining properties for mast cells, mucins, and chondrocytes. It can stain different components of plant tissues and cells in different colors and is also used as a diagnostic aid to identify malignant lesions, such as cancer.
- Stains connective tissue mucins (especially acid mucins) purple to red, with a blue background.
- Causes mast cell granules to stain purple due to the presence of heparin and histamine.
- Stains amyloid blue, which then shows a bright red birefringence under polarized light.
- Suitable for staining frozen sections due to its rapid procedure (10-20 seconds) and improved clarity of cells.
- Can also dye the lignins of plants blue-green, the phloem blue-purple, and the remaining plant parts pale blue-green.