On Mon, 28 Feb 2000, Tony Henwood wrote:

> Wouldn't the melanin also reduce the silver, since it argentaffilic?
> >                          ....  There are also silver
> >   methods for amplifying the brown product, but these are
> >   quite complicated procedures.

  A good point Tony. The argentaffin reaction of melanin is with
  ammoniacal silver solutions, which are quite strongly alkaline. 
  The  amplification of DAB is done with a physical developer
  of the Gallyas type, at somewhat less alkaline pH. My notes
  on 3 papers (1986 to 1998) don't mention melanin. Perhaps the
  authors didn't try their methods on skin or substantia nigra.

  I would guess that you are right, and melanin might well
  get co-amplified along with DAB in the silver enhancement
  methods. Perhaps a message will come in from someone who
  has tried the method on melanin-containing material.

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