[Histonet] Colloidal Iron

[John Kiernan]

There's just the one Hale's (1946) method, also called
the dialysed iron technique because if you make
the original reagent yourself you have to dialyse 
the ferric hydroxide sol. Detailed instructions are
given in Pearse's Histochemistry (any edition).
There have been several variants of the principal
reagent. In all the techniques the bound ferric
iron is made visible by a Prussian blue reaction
with potassium ferrocyanide.

In Chapter 10 of the latest (2002) edition of
Bancroft & Gamble's "Theory and Practice ..." by
Barbara Totty, the method attributed to Hale (1946)
uses a more easily made colloidal iron sol that
does not need to be dialysed. A more detailed 
reading of Pearse (3rd ed) shows that this is close 
to the reagent of G.Muller (3 papers in Acta Histochem
vol 2, 1955-56, not seen by me; they'll be in
German). This colloidal iron sol quickly became more 
popular than Hale's reagent not only because it was 
easier to make but also because it was more specific 
for acid mucosubstances. The not-dialysed colloidal
iron solution, unlike Hale's, does not stain nuclei
and there is no "background" cytoplasmic blue colour 
in renal tubules.

Both Pearse and Totty point out that colloidal iron
staining does the same job as alcian blue (pH 2.5)
but provides a darker blue product and also some 
nonspecific staining. It's more sensitive and less
clean.

"Hale's colloidal iron" (subject of the original 
enquiry) is probably not an appropriate name for this
technique, which has been significantly improved
since 1946. Pearse seriously questioned its
histochemical
specificity despite recognizing the improvements made
by Muller and several others. 

Alcian blue is easier to use and can be incorporated 
into many other rational mixed staining procedures
for mucosubstances. I know nothing about renal
carcinoma 
chromophobes. If they can be stained with colloidal
iron
they must be basophilic, not "chromophobic."  There are
very few genuinely chromophobic (unstainable)
cytoplasms.
-- 
-------------------------
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
   kiernan <@t> uwo.ca
   http://publish.uwo.ca/~jkiernan/
__________________________________
lena spencer wrote:
> 
> Hi All:
> One of my Pathologist's has requested a Hale's Colloidal Iron for renal cell
> carcinoma chromophobes.  I am familiar with colloidal iron for
> mucosubstances, but he feel's that this is not the same stain.   The article
> stated that the diagnosis is made from the colloidal iron stain  or from
> electron microscopy .  This Pathologist is requesting that I post on the
> histonet for additional information or for someone out in histoland who is
> performing this procedure.
> Your is insight would be greatly appreciated.
> Lena