Have you ever not done this with a MW, we do classic, old fashioned purist
long GMS without MW and Pneumocystis works without problems, in fact is
very easy to stain. One of our research groups studies this organism in
lungs. Try the method the old fashioned purist way and see what happens. 

Could it be that hot chromic acid is over-oxidizing your Pneumo cell wall
resulting in inconsistent results. This step could be done at room
temperature - it doesn't add that much time to protocol.  

When we did use a MW, we agitated/stirred MW heated solutions BEFORE
immersing sections, to make sure temperature is evenly dispersed over
section/slide. A tongue depressor or plastic Pasteur transfer pipette works
nicely.  
Gayle Callis
MT,HT,HTL(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology 
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367 (lab with voice mail)
406 994-4303 (FAX)



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