Re: Urea for Tol. Blue Stain

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From:"J. A. Kiernan" <>
To:Beckers <>
Content-Type:TEXT/PLAIN; charset=US-ASCII

On Mon, 12 Jun 2000, Beckers wrote:

> I saw mention on the net that urea helps intensify Toluidine Blue staining.
>  Where can one get urea and how does it come-liquid/powder form?  I do Tol.
> Blue every day and fading can be a problem.  It would be nice to be able to
> enhance this stain.  Thanks in advance.

  Urea is a white powder, harmless and extremely soluble in water. If you
  mix it with any dye solution it will generally suppress staining,
  especially when the mechanism is not the attraction of coloured dye
  ions to oppositely charged ions in the section. Added urea won't
  intensify (darken) staining, but it might enhance contrast by reducing
  the attraction of dye ions or molecules to non-ionized  parts of the
  tissue being stained. 

  For any specific technique involving dye + urea you should carefully
  read the original publication.  The interactions of urea with the
  dyeing process are discussed in two of Richard Horobin's books:
: "Histochemistry" (1982) and "Understanding Histochemistry" (1988).
 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1

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