Dictionary » C » Counterstain




The dye or stain that is used to differentiate one component or cellular structure from another, or to differentiate an entity from another in a specimen. It does so by colouring a portion of a specimen (e.g. of a tissue or of a cell) that remained uncoloured following the first staining using a dye of different color.


For instance, in Gram staining, two dyes are used: the Crystal Violet and Safranin. The Safranin is the counterstain used in this method. The Gram Staining is used to distinguish Gram positive bacteria from Gram negative bacteria.


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Definition of Primary Stain?

... to Gram Staining; 1. Apply Primary Stain (Crystal violet) 2. Add Trapping agent (Gram's Iodine.) 3. Decolorize (With alcohol or acetone) 4. Counterstain (Safranin or basic Fuchsin) Anyone able to assist? Thanks in advance :)

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by Aric
Fri Oct 02, 2009 5:27 pm
Forum: Microbiology
Topic: Definition of Primary Stain?
Replies: 1
Views: 20422

Gram stains

... in gram staining? I think it would be colorless since the dye would not be trapped inside the cell wall??? Why doesn't methane blue work as a counterstain vice safranin?

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by yvette
Sun Oct 16, 2005 6:49 am
Forum: Microbiology
Topic: Gram stains
Replies: 2
Views: 2813

Gram Stain

... in the primary stain (crystal violet) being retained then it is +. If the gram stain results in the primary stain being decolorized and the counterstain (safranin) being retained, then it is -.

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by b_d_41501
Tue May 31, 2005 11:31 pm
Forum: Microbiology
Topic: Gram Stain
Replies: 4
Views: 6026

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