Orange G Solution (OG-6) is a component used in the Papanicolaou (PAP) Stain, which is designed to differentiate between a variety of cells in vaginal smears for detection of vaginal, uterine and cervical cancer. In addition, this procedure is valuable for staining a variety of other bodily secretions and cell smears. Orange G Solution is responsible for the orange coloration in high keratin cells. The procedure was developed in the early 1940's by George Papanicolaou.