Checked the pH of your formalin lately? Might be hematin (or formalin)
pigment. Try immersing the deparaffinized slide in 70 % ethanol containing 3
mL of ammonium hydroxide for 30 min - 3 hours at room temp. Rinse well with
water. Rinse with 1 % acetic acid(aq). Rinse with water again and proceed
with the staining.
 Good luck, Donna Montague
-----Original Message-----
From: Mark Schrenzel [mailto:mschrenzel@sandiegozoo.org]
Sent: Wednesday, March 21, 2001 1:17 PM
To: histonet@pathology.swmed.edu
Subject: yellow rbc


Dear Histonetters,

We are getting yellow staining of red blood cells in formalin-fixed
mammalian tissues. Does anybody have any experiences or ideas about this?
Thanks very much.

Mark Schrenzel
Zoological Society of San Diego
Center for Reproduction of Endangered Species
P.O. Box 120-551
San Diego, California 92112
email: mschrenzel@sandiegozoo.org