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Papanicolaou (Pap) stain

Reviewer: Nat Pernick, M.D., PathologyOutlines.com, Inc. (see Reviewers page)
Revised: 22 June 2011, last major update June 2011
Copyright: (c) 2006-2011, PathologyOutlines.com, Inc.


● Multichromatic staining histological technique developed by George Papanikolaou
● Classic form involves five dyes in three solutions (IHC World, Wikipedia)
● An alcohol dried preparation that produces better nuclear detail than air fixation
● Stains ribosomes blue green, particularly in parabasal cells, mesothelial cells and metaplastic squamous cells
● Stains metabolically inactive cells pink, such as superficial cells
● Stains keratinized cells or thick specimens orange (benign or malignant)
● Must fix smear quickly and stain carefully; air dried smears are inadequate

Clinical images

Smearing and slide preparation

Procedure for staining

Cytology images

Conventional smears-examples of good cellularity

End of Cervix-cytology > Papanicolaou (Pap) stain

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