Pontacyl blue black 10 B is a synthetic dye used in histology and cytology to stain cell structures. In an aqueous solution, pontacyl blue black is often used in combination with potassium dichromate.

The dye penetrates the tissue and allows clear delineation of different cell structures. It is often used in combination with other dyes to selectively stain different tissue components and achieve better visualization of cell structures. Pontacyl Blue Black 10 B is particularly suitable for staining proteins, especially nucleic acids and membrane proteins. The added potassium dichromate in the aqueous solution serves as an oxidizing agent, which improves the staining intensity and stability of the dye.