Methylene blue chemically named tetramethylthionine chloride, is a thiazide based alkaline dye. Its molecular structure contains positively charged nitrogen atoms, which can bind with negatively charged substances inside the cell to achieve staining.

Unna Alkaline Methylene Blue Staining Solution is mainly composed of methylene blue, potassium carbonate, etc. It has an alkaline pH and is mainly used to display transparent cartilage. This method is the best staining method for 6-8 month old fetal phalanges, and non decalcified paraffin sections can also be stained. In addition, it can also be used for staining mast cells, which need to differentiate to a light background after staining. This staining method has a short staining time, clear comparison of results, and simple operation. This reagent is only used in the field of scientific research and is not suitable for clinical diagnosis or other purposes.