Lisa Hazelwood is lucky to get an answer because she wrote:
_without anything in the Subject Line of the email._
_Grrrrr!_

> My supervisor has been told about a method to stain myelin using colloidal
> gold and want's to try it.  The person who told her about the method
> refered to the Cajal method.  I've looked through the literature and cannot
> seem to find any reference to colloidal gold and myelin staining.  Is she
> thinking of a method that:
> 
> a) uses colloidal gold conjugated to either a primary or secondary antibody
>    i.e. tracers for EM; or
> b) a method that uses gold chloride.

Lisa, you clearly know much more about histotechnology than
either your boss or the "person who told her about the method."

Probably I'm older than they, so I can provide historical help.

Cajal (1852-1934) was a Nobel prize winner, but he died 8 years
before the first immunohistochemical method and about 40 years
before colloidal gold labelling of antibodies. He did invent a
gold chloride staining method (it also uses mercuric chloride), 
but that method is for showing astrocytes, not myelin. 

The only gold chloride method for myelin that I know about is
that of Schmued,LC 1990 J Histochem Cytochem 38:717-720. I've
read the paper but have not tried the technique because there
seems to be no advantage over cheaper ways to stain myelin.

The price of gold chloride from chemical suppliers is 
ridiculously high in relation to the price of the metal.
Never throw out your old gold solutions. It is easy+++ to
recycle them in the lab and save $$$. Here's how:
Recycling procedure for gold chloride used in neurohistology. 
Stain Technology 52, 245-248 (1977).
-- 
-------------------------
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
   kiernan@uwo.ca
   http://publish.uwo.ca/~jkiernan/