Andrea Grantham, HT(ASCP asks about DPX.

It's a traditional synthetic, non-fluorescent, resinous
mounting medium, also sold as DePeX. The abbreviation
is from its composition:

D for Distrene-80, which was a make of polystyrene.
   (presumably with M.W. 80,000).
P for plasticizer (either tri-o-cresyl phosphate
   or dibutyl phthalate).
X for xylene, the solvent.

(Information from Lillie & Fullmer's "Histopathologic
 Technic ... 1976)

DPX is very good, but sometimes you get a batch 
with little droplets in it, and that's bad. I changed 
over to a poly(methyl methacrylate) medium about 5 
years ago (either Cytoseal or Entellan). DPX was rather 
nicer to handle; when dried, it pealed off easily from
places it wasn't supposed to be.

-------------------------
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
   kiernan@uwo.ca
   http://publish.uwo.ca/~jkiernan/