We are several persons in the lab who perform immunohistochemical 
revelation on floating spinal cord sections after PAF4% transcardiac 
perfusion (with or without picric acid). It often appears  a staining of 
blood vessels which seems to be non specific. It's hard to explain because 
it does not appear on sections incubated without the first antibody -so it 
should be specific- but the staining is smooth and fills the entire cavity 
of the blood vessels. Moreover it often does not concern the entire section 
and is regionalized. We have this problem either with fluo or with 
perox-revelation (but it is more frequent with the latter).
I've tried to change my protocol (with or without serum in the buffer), but 
it doesn't change anything...
I've made IHC on brain and medulla sections of the same animals and this 
problem appeared very rarely .

Does someone have an idea ?

Sandra
PhD student