John Kiernan wrote:
"Note that the name PLP was poorly chosen by the inventors
of this mixture, because the solution does not contain
any paraformaldehyde. For a good paper on how it works,
see DC Hixson et 4 al 1981 J Histochem Cytochem 29:561-566."

I beg to differ with this statement.  I used PLP fixative for years when I was working in a research lab and it is made with paraformaldehyde.  A quick search produced the following reference if you're interested:
MacLean IW, Nakane PK.  Periodate-lysine-paraformaldehyde fixative.  A new fixative for immunoelectron microscopy.  J Histochem Cytochem 1974;22:1077-84.

Carrie Kyle-Byrne, HT(ASCP)
CAHFS-UCDavis