Re: Rat Tissue Processing-II

From:"John C. Dennis" <dennijc@vetmed.auburn.edu>

Dear Cyrla

I perfuse my rats through the left vetricle with 0.9% NaCl followed by
approx. 250 ml 4%
paraformaldehyde in PBS at pH 7.4.  I mix heparin with the anesthetic that
is delivered IP.  I also clamp the descending aorta before cutting the
right atrium.

After perfusing the animal, I remove the head, trim away all the soft
tissue and put the skull in PBS for a few minutes.  Remove bone and cut
the brain in two along the mid-sagital line and post fix O/N at 4 deg C.

I found that the rough edge effect (venitian blind effect?) was
circumvented by reducing the time in paraffin and xylene in our Tissue
Tek.  The fixation has always been adequate.  I've always assumed that a
good perfusion is critical and that overnight fixation by immersion in 4%
paraformaldehyde as just the way it was done and further processing could
wait until the next day since it was quitting time anyway.

John Carroll Dennis
Anatomy, Physiology, and Pharmacology
109 Greene Hall
Auburn University, AL  36849






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