Re: [Histonet] Melanin and Azure B

From:"John A. Kiernan"

If the pigment is already black, it doesn't need
to be stained. Melanin is bleached by 3% hydrogen
peroxide ("10 volumes available oxygen"), 3 to 36
hours at room temperature. (Control slide in
water.) Bleaching by H2O2 is considered a
reasonably specific test for melanin. 

Lillie & Fullmer (p.524) comment that melanin is
stained dark green by 0.05% azure A at pH 1 for 20
min. This coloration resisted methylation, so it
may be due to oxidized cystine in an associated
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
Jackie M O'Connor wrote:
> Hi -
> I found a couple of old posts about being able to stain melanin with 1%
> aqueous Azure B.  Can someone shed light on why this isn't seeming to work
> for me?
> I'm basically trying to identify a black pigment in FFPE that looks like
> melanin without having to depend on HMB45.  Any takers?
> Jackie
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