On Fri, 25 Feb 2000, Wilhelms, Margaret B wrote:

> I would like to know if anyone uses a dye or ink to mark certain structures
> at trimming that will stay in place and be visible after processing (at
> cutting).  I am trimming primate eyes and would like to mark the macula (and
> fovea) or the outside of the eye where the macula is so that it would be
> easier to obtain at cutting.  I think I need a color other than black.  Can
> anyone suggest anything?  Does anyone know of a dye or ink that can be
> applied after processing just prior to embedding? 

  I haven't done this, but the theoretically obvious answer is a
  strong (?5%) solution of alcian blue 8GX (a dye used in most
  histo(path)ology labs) in 3% acetic acid. A tiny drop could be
  applied to a surface, left for several minutes to stain the 
  connective tissue matrix etc, then blotted off. Subsequent 
  exposure to alkali (ammonia fumes might do it) should convert
  the alcian blue into copper phthalocyanine, a pigment that is 
  insoluble in pretty well everything.

  A droplet of India ink might be better, but you did say black
  was not wanted for the colour of the label.

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