Hello Ian and Histonetters,

I read your message about microwave processing with great interest.  I have 
been investigating microwave technology for the past year during the 
development of the TBS Laboratory Microwave.  I, too, wondered about the 
effect that microwaves have on exposed specimens.  There is still a lot of 
speculation among the experts as to how the specimens are affected by the 
microwaves, but there is overall agreement that microwave exposure stimulates 
the diffusion of solutions and enhances reaction rates  due to internal 
heating.  The most widely accepted theory is that the microwave energy is 
converted to kinetic and chemical energy.  The kinetic energy is brought 
about by the rapid oscillation of dipolar molecules, causing internal heat.  
Although microwaves can't ionize molecules and are too small to break 
molecular bonds, it is possible that the hydrogen bonds are redistributed 
(chemical energy).  The microwaves probably affect the bound water that 
physically separates macromolecules.  Exposure causes thinning of the bound 
water the layers.  This allows them to unwind and form new crosslinks, 
resulting in the formation of different configurations.  

Donna Willis and Andrea Grantham and I will be presenting a workshop on 
microwave processing at NSH in Milwaukee.  During the workshop we physically 
demonstrate that there is, indeed, a microwave effect.  I will be happy to 
supply you with the experiment if you are interested.  It is quite dramatic.  
There will also be an article in the September edition of ADVANCE for 
Administrators of the Laboratory that covers microwave tissue processing.  I 
hope that it will offer additinal information for those who are interested.

As I am sure you have noticed, the thickness of the specimen is the key to 
the required length of exposure in either a stabilization solution, fixative 
or processing solution.  It may take a little tweaking to get the procedures 
to match the results that you are familiar with, but I would encourage you to 
keep trying.  You should be able to get excellent results in a fraction of 
the time.

Best of luck in your endeavors.

Jan Minshew
Technical Director
TBS