On Fri, 12 Mar 1999, Sue.Hacker wrote:

> Has anyone any experience in acetylcholinesterases. we are looking to 
> demonstrate Langerhans cells in bovine tissue using the above technique.
> We are looking for an up to date method, Bancroft mentions the Gerebtzoff
> method 1959. We wondered if there was a commercial kit available.

                                                  12-3-1999
   Dear Sue,

   There are two groups of methods for AChE. The earlier ones,
   derived from Koelle & Friedenwald (1949) are done in two stages, 
   with production of copper sulphide as the final reaction product.
   (Gerebtzoff's method is one variant of the Koelle procedure.)
   The others, following Karnowsky & Roots (1964), are "self
   colouring," and deposit copper ferrocyanide directly from the
   incubation medium. For nervous tissue, central and peripheral,
   these are among the easiest and most reliable of all enzyme
   histochemical methods. There are all kinds of technical
   variations, mainly to increase sensitivity, and you can use
   inhibitors to check the biochemical specificity. These methods 
   are usually used on frozen sections of specimens fixed in
   formaldehyde overnight in the fridge. Soaking in sucrose for
   cryoprotection is also helpful though not always necessary.

   Technical instructions are given in all textbooks of
   histological/histochemical techniques. As for most methods, 
   the most critical, scholarly treatment is in Pearse's 
   Histochemistry (Vol 3 of the 4th ed., but Vol. 2 of the 3rd
   isn't significantly out of date for the average user of
   AChE histochemistry).

   The chemicals used are not very expensive or difficult to weigh
   and measure, so it would probably be a waste of money to buy a
   kit, even if available. Why pay someone else an hour's wages 
   to do what you could do yourself in 5 minutes? 

   Hope this helps.

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1