Janus Green B is a basic dye and

vital stain A vital stain in a casual usage may mean a stain that can be applied on living cells without killing them. Vital stains have been useful for diagnostic and surgical techniques in a variety of medical specialties. In supravital staining, living cells ...

used in

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vi ...

. It is also used to stain mitochondria supravitally, as was introduced by

Leonor Michaelis Leonor Michaelis (16 January 1875 – 8 October 1949) was a German biochemist, physical chemist, and physician, known for his work with Maud Menten on enzyme kinetics in 1913, as well as for work on enzyme inhibition, pH and quinones. E ...

in 1900. The indicator Janus Green B changes colour according to the amount of oxygen present. When oxygen is present, the indicator oxidizes to a blue colour. In the absence of oxygen, the indicator is reduced and changes to a pink colour.

References

Staining dyes Azo dyes Phenazines Chlorides Aromatic amines Anilines Diethylamino compounds {{organic-compound-stub