On Fri, 19 Jan 2001, Wilhelms, Margaret B wrote:

> 1) Can anyone tell me about a stain for motor end plates that works and is
> not too difficult to do in large quantities?

By far the easiest and least expensive method is to stain frozen sections
(preferably fairly thick - 40-60 um - by a histochemical method for
acetylcholinesterase (AChE) activity. You do not need a method of high
histochemical specificity. An indigogenic method, using one of the 
haloindoxyl acetate substrates, is excellent even though in principle it
detects all other carboxylic esterases and possibly also some peptidases. 
In fact, the end-plate AChE is the only staining seen with brief
incubation (15-30 min). Alternatively use the Karnovsky & Roots method,
with acetylthiocholine (AThCh) as substrate. This too is a one step
rapid method, giving a brown end product. It is much faster and easier
than Koelle's original 2-stage AThCh technique and its many derivatives. 
Also the K & R method does not use ammonium sulphide, which stinks.

The blue product of an indigogenic method for esterases is unchanged
by counterstaining with a silver method for to show the axxonal
(presynaptic) component of the motor end plate. Counterstaining of
Karnovsky-Roots preparations with silver is disappointing: there is
weakening and even loss of the AChE reaction product. I haven't tried
combining AChE activity staining with an immunohistochemical method
for axons, but my guess is that they would go together well. A blue
haloindigo would contrast well with the brown end-product of an
immunoperoxidase-DAB procedure. 

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