Papanicolaou Stain

Papanicolaou Stain: A Comprehensive Guide

Papanicolaou Stain

  • Specifications: 3x250mL, 1000mL (Box)
  • Intended use: Intended for histocytological staining of exfoliated cells
  • Store temperature: 10℃~30℃

The Principle Behind Papanicolaou Stain

At the heart of Papanicolaou staining lies a profound understanding of cell composition. The nucleus, rich in acidic substances, exhibits a strong affinity for basic dyes. Conversely, the cytoplasm, brimming with alkaline substances, is drawn to acid dyes. By harnessing this inherent characteristic, the Papanicolaou staining solution elegantly colors cells, rendering their structures vividly visible. The outcome is a translucent, bright cytoplasm, with clear differentiation between various particles and the nucleus chromatin. This technique proves to be a beacon for identifying abnormal cells, making it an invaluable asset in the early detection and diagnosis of lesions and tumors.

Main Components

Papanicolaou staining solutions come in two primary variants: EA36 and EA50, each with a distinct composition aimed at achieving optimal results. The key ingredients include:

  • Hematoxylin Solution (Harris): This solution, centered around hematoxylin, forms the foundation of the staining process.
  • Orange G Solution: Infused with Orange G, this solution contributes to the nuanced coloration of the stained cells.
  • Bright Green, Eosin: The inclusion of these components further enhances the visual contrast, enabling precise analysis.

Test Procedure

The journey of Papanicolaou staining entails meticulous steps to ensure accurate outcomes. Here’s a breakdown of the test procedure for both EA36 and EA50 solutions:

  • Fixation in Ethanol: Begin by immersing smears in 95% ethanol for 15 minutes, followed by sequential dips in 75% or 80% ethanol and 50% ethanol, each lasting 30 seconds.
  • Hematoxylin Staining: The crucial step of hematoxylin staining takes 3-5 minutes, during which the cells absorb the dye.
  • Differentiation and Blueing: The application of hydrochloric acid ethanol and subsequent blueing with running water or dilute lithium carbonate solution helps achieve the desired contrast and coloration.
  • Orange G Solution Application: Apply Orange G Solution for 1-2 minutes, enhancing the diversity of coloration.
  • Final Staining: The cells undergo a final staining phase, using EA36, EA50, or OG/EA solutions for 5-8 minutes, ensuring optimal clarity.
  • Dehydration and Sealing: Conventional dehydration and transparent sealing with neutral resin conclude the procedure, preserving the stained specimens.

Result Interpretation

  • Epithelia: Nuclei appear indigo, nucleoli in red, keratinized cells are pink, fully keratinized cells manifest orange, and pre-keratinized cells sport shades of sky-blue or light green.
  • Erythrocytes: Erythrocytes exhibit a vermeil or salmon pink hue.
  • Leukocytes: Cytoplasm is adorned in sky-blue or light green, while nuclei gleam indigo.
  • Mucus: Mucus stands out in shades of sky blue or pink.


To harness the full potential of Papanicolaou staining, adhering to precautions is paramount:

  • Oxide Film and Precipitation: Regularly remove the oxide film and filter the hematoxylin solution. Dilute lithium carbonate solution aids in the blueing process.
  • Temperature Sensitivity: In colder temperatures, extend the staining time of Hematoxylin stain (Harris) for optimal results.
  • Contrast Enhancement: The color separation process is critical; over-differentiation may lead to light-stained nuclei.
  • Residue Removal: Thoroughly wash away Orange G residues with 95% ethanol to ensure unaffected staining.
  • Expiration Date: Always adhere to stated expiration dates and store reagents appropriately to maintain their efficacy.
  • Professional Handling: This stain is best utilized by professionals, and meticulous adherence to instructions is vital for accurate results.
  • Waste Disposal: Dispose of waste in accordance with hospital or environmental guidelines.
  • Information on Packaging: Relevant production and expiration details are conveniently displayed on the outer packaging.

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