Mast Cell stain solution (toluidine blue method)

Mast cells are common cells in loose connective tissue, often distributed in groups along small blood vessels and lymphatic vessels. They are also commonly found around the bronchi and interlobular ducts of the pancreas. Generally, the cells are large, about 20-30 um in diameter, round or oval in shape, with small nuclei and cytoplasm filled with coarse and metachromatic eosinophilic granules.

The cations in Toluidine Blue O have a dyeing effect, and the acidic substances in tissue cells combine with the cations to be stained. Toluidine Blue O also contains two auxochromophores, which can promote the ionization of the dye into salts, help the chromophore to produce staining power on the tissue, color the tissue cells on the slice, and dye the cell nucleus to make it blue. In clinical practice, Toluidine Blue is often used to stain chondrocytes and mast cells.