Definition of Primary Stain?

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Definition of Primary Stain?

Post by Aric » Fri Oct 02, 2009 5:27 pm

I hope this is in the right section, as it does pertain to Microbiology.

I've spent some time looking around, and I cannot find a definition for "Primary Stain" anywhere whatsoever. Im wondering if any of you are able to have any luck?

Simply enough, im just looking for an actual definition to the term 'Primary Stain' in relation 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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Post by canalon » Fri Oct 02, 2009 6:28 pm

The primary stain is the stain that will actually stain what you want to see. in the case of the Gram stain, that is the particular structure of the cell wall of the Gram+ bacteria. Safranin is a non specific stain that will just allow the visualization of the bits that have not already been stained. Gram+ bacteria do also take up the safranin, but you cannot see it behind the deep purple of the Crystal violet/iodine complex.

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