[Histonet] Formalin Fixation times for IHC samples

[Anne C Lewin]

Could I get a general concensus from Histoland about the amount of time 
needed to fix a sample for IHC without over-fixing?  My training/journal 
searches  have led  me to believe that the longer a sample is in 
formalin, the stronger the protiens are cross-linked, and the more 
difficult it is to break those bonds with antigen retreival and get your 
antibody to the target.  I generally tell the scientists in my 
department to fix overnight (most samples vary from about the size of a 
pea to a lima bean), and then to transfer to 70% Ethanol for me to 
process for paraffin.  The total time in fixative tends to be around 24 
hours.  Morphology has always been great, and my IHC's work well.  This 
question is mainly for my information, since I have used the same tissue 
prep protocol for a few years now, I want to make sure I am keeping up 
with current opinions.
Thanks!
-Anne