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David Stuss wrote:

> I'm interested in tracing full dendritic arbors of single 
> dye-injected cortical neurons (in PFA-fixed mouse brain) and hence 
> require sections 200-300 um thick. My aim, if at all possible, would be 
> to differentiate cell subtypes by immunolabeling deep in the tissue 
> slice, either to identify previously dye-filled neurons, or to identify 
> neurons for tracing. 

Dear David--

What you want to do may be trivial or it may be impossible: in my 
experience it depends largely on the particular primary antibody.  Some 
antibodies penetrate easily through tissue; others penetrate almost not 
at all.  Try yours and see what happens.

Running your tissue through a freeze-thaw cycle will help penetration, 
as will use of detergent in at least some cases.

In my experience, fluorophore-labeled streptavidin penetrates tissue 
very easily, thus labeling a neuron filled with (say) Neurobiotin or 
biocytin should be easy.

Good luck!

Martin Wessendorf

-- 
Martin Wessendorf, PhD 	   (612) 626 0145 (office)
Associate Professor	      (612) 624 2991 (lab)	
Dept Neuroscience 	      (612) 624 8118 (FAX)
Univ Minnesota	        e-mail: martinw(at)umn.edu