Diana - It depends on what you want to do in the oven.  If you use it for
special stains and small techniques (like setting mounting media, etc.), a
household MW will surfice.  If you are going into techniques like
processing you will have to get a laboratory type.  The new laboratory MW
have true variable wattage, venting, and (it's new) vacuum.  I have tried
processing for years in a household type, and although it can be done, it
is so much easier and better in the laboratory types.  There are two
American manufacturers - Ted Pella (Pelco) and Energy Beam.  If you would
like any personal opinions on either, please e-mail me directly.

Cheryl Crowder
LSU School of Vet. Med.