[Histonet] Oil Red O

John Kiernan jkiernan <@t> uwo.ca
Thu Feb 17 14:22:19 CST 2005

Extraction of haemalum must mean that the aqueous medium
is acidic. The acidity might be there initially (it's
a good thing for some stains). It may come from 
atmospheric CO2 (distilled water usually has pH=5 for
this reason), or it may be due to aluminium and sulphate
ions coming from the stained section. (All haemalum
solutions contain a large excess of aluminium
sulphate over & above the amount that complexes with
haematein; this is necessary for the stain to work

Suggested remedy:
After counterstaining, blueing and washing, rinse the 
sections in a slightly alkaline buffer. (Phosphate, 
pH 7.4 should be OK.) Then shake off excess buffer 
and apply the aqueous mountant and coverslip.
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
"Till, Renee" wrote:
> Hello. We have been doing some Oil Red O stains on cryosections of aorta
> and have been having problems with the hematoxylin leaching out during
> mounting. We have tried several different aqueous mounting medias and
> none have corrected the problem. Could it be the tissue or maybe the
> type of hematoxylin? Another lab has been doing the stain on liver and
> hasn't had any problems.

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