RE: toluidine blue/Na borate

From:"Smith, Allen"

The sodium borate opens the resin for a few nanometers so that more
toluidine blue solution can penetrate the section.  The greater availability
of toluidine blue makes metachromasia possible.  Toluidine blue stains
metachromatically when the tissue contains closely-spaced repeating units of
acid.  The closely spaced acid residues hold the toluidine blue molecules in
a stack that absorbs a lot of blue light, allowing enough red to pass
through that the net effect is purple.  [The reason for the stack absorbing
blue light is not well understood.  The best guess is that blue and only
blue light has enough energy to kick electrons across the narrow gap between
the toluidine blue molecules in the stack.]

Allen A. Smith, Ph.D.
Barry University
School of Graduate Medical Sciences
    Podiatric Medicine and Surgery
Miami Shores, Florida  33161-6695 

-----Original Message-----
From: []
Sent: Thursday, September 19, 2002 2:26 PM
Subject: toluidine blue/Na borate

Hey histonetters!!

I have a question or two.  What is the difference between 1%toluidine blue
alone and 1% toluidine blue added to 1% Na borate.  I know that toluidine
is used on paraffin sections for mast cells.  I looked in histonet archives,

but did not find an answer to my question.  Does anyone know why na borate
added? I know that 1% toluidine blue alone is dark blue with light blue;
na borate and you get purple and blue.  

Any help appreciated!!


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