Re: Warthin-Starry Addendum
From: | "J. A. Kiernan" <jkiernan@julian.uwo.ca> |
On Mon, 6 Nov 2000 Ballnclaw@aol.com wrote:
> I have found mention in literature of a post treatment using a 1% aqueous
> potassium ferricyanide solution to reduce background staining after the
> Warthin-Starry technique. It may also be helpful!
> J.D., Bancroft, Theory and Practice of Histological Techniques, 3rd ed.,
> Churchill Livingstone, Inc., January 1990.
Potassium ferricyanide oxidizes silver (coloured or black
colloidal metal) to silver ferrocyanide (a white insoluble
solid that can be dissolved by a solution containing sodium
thiosulphate). The ferricyanide and thiosulphate are
combined in the same solution in Farmer's reducer,
which is used to lighten overexposed black & white
negatives or prints. Reduction, in this context, means
reducing the amount of silver in an image. (Chemically
speaking, this is oxidation, not reduction!) Farmer's
reducer or a similar mixture can be used to lighten
any silver staining method.
Ferricyanide acts first on the smallest silver particles
in a stained section or smear. This can clear a yellow
or light brown background. The largest colloidal silver
particles (black) are the last to be extracted. The
method will not work on preparations that have been
gold-toned.
John A. Kiernan,
Department of Anatomy & Cell Biology,
The University of Western Ontario,
LONDON, Canada N6A 5C1
<< Previous Message | Next Message >>