OG-6 reagent, Pap 2A is an alcoholic solution of Orange G dye with added phosphotungstic acid (PTA). The first step in using the Papanicolaou staining method implies nuclear staining with a hematoxylin solution, and next two steps consist of contrast staining using the monochromatic OG-6 reagent and one of the polychromatic EA reagent formulations consisting of two acid dyes, the Eosin Y and Light Green SF. The Orange G molecule stains the cytoplasm, and in later stages of the procedure it remains only in the mature, keratinized cells that turn different shades of orange. The third step consists of using of one of the polychromatic EA solutions that stains the unstained cellular components, such as squamous cells, nucleoli, cilia, and erythrocytes. Test samples can be gynecological and non-gynecological, such as sputum, urine, and cytological puncture samples. In order to obtain optimal staining results, the properties of OG-6 reagent, Pap 2A are completely in accordance with other BioGnost’s reagents used for cytological staining acc. to Papanicolaou – OG-6, Pap 1A reagent, EA 31, Pap 3A reagent, as well as alternative counterstain polychromatic stains, such as EA 50, Pap 3B reagent and EA 65, Pap 3C reagent.