Papanicolaou staining--a review

Area of Science:

• Cytopathology
• Histochemistry
• Cell Biology

Background:

• The Papanicolaou stain is a cornerstone in cytological diagnosis.
• Understanding its technical aspects and underlying chemistry is crucial for accurate interpretation.
• Historical evolution provides context for current methodologies.

Purpose of the Study:

• To review the technical aspects and histochemistry of the Papanicolaou staining technique.
• To propose a mechanism for the differential counterstaining observed (orangeophilia vs. cyanophilia).
• To discuss recent quantitative studies, procedural modifications, and alternative staining methods.

Main Methods:

• Historical tracing of staining techniques from Mallory and Masson to Shorr.
• Discussion of the histochemistry of Papanicolaou staining solutions (aluminum-hematoxylin, OG, EA).
• Analysis of the aluminum-hematein chelate structure and function.

Main Results:

• A proposed mechanism for differential counterstaining involving cytoplasmic density, dye molecular size, and phosphotungstic acid inhibition.
• Consideration of recent quantitative studies on Papanicolaou-stained cells.
• Outline of modifications to the Papanicolaou procedure.

Conclusions:

• The differential staining in Papanicolaou techniques is attributed to a combination of cellular and dye properties.
• The review provides a comprehensive overview of the Papanicolaou stain, including its historical context and future directions.
• Alternative staining methods are discussed, offering broader perspectives in cytopathology.