In my experience it depends entirely on what CD's you're looking at. =
CD2 and CD22, for example, are very sensitive to fixation in
formaldehyde/paraformaldehyde and can disappear completely, whereas CD3 i=
s
pretty robust.
I did have a list of sensitivities of "standard" CD's that I produced a
few years ago - can't seem to lay my hands on it though.
Of course, it also depends on your fixative concentrations and timings.
Wal Sharp
SQU
Oman