As long as the tissue has been washed in buffer, or dehydrated 
through an ethanol series, there is no problem. Any remaining osmium 
is bound to the tissue components, and reduced to the metallic form. 
It'll just be another lipid stain.
Trying to remove the bound osmium would cause all sorts of problems 
with your specimens.
Phil

We are working with researchers who would like to do EM and paraffin 
embedding on the same piece of tissue.  We will receive the tissue 
following the EM procedure.  Is there any risk of toxicity from the 
osmium during decalcification in EDTA, processing, embedding, 
sectioning, or staining?  If so, is there a way to remove the osmium 
or make it non-toxic for these procedures?

Anne Undersander HT(ASCP)
Vet. Med./Animal Science
University of Minnesota


-- 
Philip Oshel
Supervisor, BBPIC microscopy facility
Department of Animal Sciences
University of Wisconsin
1675 Observatory Drive
Madison,  WI  53706 - 1284
voice: (608) 263-4162
fax: (608) 262-5157 (dept. fax)