Connie, 
First of all, you must have some of the best fixed tissue around. Three days before trimming -  wow! Humans don't have their tissue treated so well.

I have not used microwave fixation, but as Beyer-Boon points out, the tissue must first have the fixative at the point of fixation before the acceleration of the aldehyde bonding takes place.
That is to say, the fixative must have penetrated completely into the tissue.
Assuming the bits are small (?small animal practice), I would have thought that trimming earlier, letting the blocks penetrate-fix as necessary, then finishing off with the microwave would be the way to go.


Terry L Marshall B.A.(Law), M.B.Ch.B., F.R.C.Path
Consultant Histopathologist
Rotherham General Hospital, Yorkshire
terry.marshall@rgh-tr.trent.nhs.uk


Greetings all!

I am looking into getting a microwave in my lab to fix the tissues with the
goal of getting a shorter turnaround time.  But I have some concerns about
how to be efficient with this.  For those of you who do MW fixation, 1)
what sizes are submitted for fixation? and 2)at what point are they
submitted -- i.e. does the pathologist trim the piece to be
fixed/processed, or does he let the tissue fix for some period of time
first?? 

Currently, we let our tissues fix between 48 and 72 hours before being
trimmed in and processed.  It seems to me that with MW fixation, this time
can be drastically reduced.  Thanks!

Connie McManus

Veterinary Diagnostics Lab
Utah State University
Logan, UT
USA
(435) 797-1891
fax (435) 797-2805