I use formalin fixed tissue for my controls, and they usually work quite
nicely.  I wash the tissue in running water for 1 hour before freezing, and
like you I use + slides.  I do let them air dry before rinsing off the media
(they tend to stay on more reliably!).  After staining in Oil red O, I would
try washing for 10 to 20 minutes in running water to help remove any excess
precipitate.  Unfortunately ORO's do have a tendency to be blobby depending
on the density of the tissue.

Best of luck!

Kathy Johnston
Tech II - Special Stains
Anatomic Pathology - Foothills Medical Center
Calgary Laboratory Services
Ph - 403-944-4760
Fax - 403-270-4093
kathy.johnston@cls.ab.ca


-----Original Message-----
From: Jane Hosmer [mailto:mjane@uab.edu]
Sent: Friday, November 08, 2002 12:07 PM
To: histonet@pathology.swmed.edu
Subject: Oil Red O on formalin fixed tissue - frozen


Dear Histos: Help!!!! I have many mouse tissues (livers,pancreas,muscle)
fixed in 10% Buffered Formalin. These need to be frozen, then stained with
Oil Red O. The problem I am running into is this: The stain is working, but
I am getting "blobs" of something staining also, that looks like it is
between the tissue and the slide. It is not precipitate. Should I be
washing the tissue thoroughly before I freeze in OCT???? I am picking up
the section on +slides. Do I need to let them air dry before staining or
wash them in H20? Any help would be appreciated.


Jane Hosmer HT,HTL.
mjane@uab.edu
UAB CPL Service Center
Birmingham, Al.