Re: [Histonet] Perl's Prussian blue Iron stain

From:Paul Bradbury

Hi René,

You make a valid point, however, although all staining reactions are=20
histochemical reactions, NOT all histochemical reactions are staining=20

Some of this argument may seem to be too concerned with semantics, but 
in order to have a full understanding of how tissue demonstration=20
techniques work, a precise knowledge of the reactions involved is essential.

A "staining reaction" involves bonding (in one form another) between the 
auxochromic groups of the dye molecule and the available reactive groups 
of the tissue.

The demonstration of iron, by Perls' method, or Turnbull's method, is=20
purely a chemical reaction between reactive compounds. It is an 
inorganic chemistry reaction, and the tissue itself plays no role in the 
formation of the final visible product. Exactly the same reaction may be 
seen by combining a ferric iron solution with potassium ferrocyanide in 
a glass tube.

Many people routinely talk about "staining" a tissue component. However, 
several commonly used histological procedures are not true "staining"=20
reactions. The ferric and ferrous iron "stains", Colloidal iron for=20
sulphated mucins, von Kossa for calcium (actually phosphates, 
carbonates), the silver "stains" used for reticulin, fungi, axons,=20
dendrites, etc, oil red O for neutral lipids, periodic acid Schiff (PAS) 
reaction, enzyme demonstration techniques, and immunohistochemical=20
techniques are all histochemical techniques, but none of them are=20
staining techniques.

Kamloops, Canada

'Rene J Buesa wrote:
> Dear Paul:
> Aren't ALL staining techniques histochemical reactions as well? Many 
> have poorly understood mechanisms but ALL HC stains are HC reactions.
> René J.
> */Paul Bradbury /* wrote:
> ------------------------------------------------------------------------
> Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try 
> it now. 

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