Which stain stains cytoplasm of superficial cells in Pap smear?

• A. Harris hematoxylin
• B. EA 50 stain
• C. Methylene blue
• D. OG 6 stain

Answer: (D)

The staining pattern in Pap smears comes from using multiple dyes that color different cell components. The nucleus is stained dark by Harris hematoxylin, which highlights nuclear detail. The cytoplasm of superficial squamous cells takes on an orange-yellow hue specifically because of Orange G (the OG-6 component) in the Pap stain. This dye has a strong affinity for the keratinized, eosinophilic cytoplasm characteristic of mature superficial cells, producing the distinctive orange color that helps identify those cells.

Other dyes serve different roles: Methylene blue is not the targeted Pap counterstain for this purpose, and while EA-50 (Eosin Azure) contributes to cytoplasmic staining, the hallmark orange coloration of superficial cell cytoplasm comes from OG-6.