On Thu, 12 Jul 2001, Sylvia Poulos wrote:

> Has anyone stained for desmin and followed it up with 
> Oil-Red-O?  I did so in cultured cells and the desmin 
> staining is completely covered up by the Oil-Red-O.  
> My question is- are these fat cells that are desmin 
> reactive?  are they muscle cells with large amounts 
> of lipid?

If the cell-types cannot be identified by their shapes,
why not use a different fat stain that doesn't conceal
the immunohistochemical end-product? If the IHC is 
making a brown product (such as oxidized DAB) then a
suitable fat stain would be Nile red, which is fluorescent
and can be used at a concentration low enough not to be
visible with ordinary light. The fluorescent Nile red 
technique is described by Fowler & Greenspan (1985) in
J. Histochem. Cytochem. 33:833-836. You can make Nile
red yourself in the lab, starting with Nile blue A (which
costs about $50 for 25gm and could yield 10gm of Nile red), 
or you can buy it ready-made (about $50 for 100mg; this 
should be enough for fluorochroming the lipids in large 
numbers of sections every day for a hundred years).

----------------------------------------
John A. Kiernan
Department of Anatomy & Cell Biology
The University of Western Ontario
London,  Canada   N6A 5C1
   kiern