Dear Jennifer,

	Depending on the staining you wish to do on your tissue it is possible to
over fix.  This is expecially true for immuno & some histochemical stains.
Since you are using a combined fixative, & that glutaraldehyde is permanent
& does not wash out, why not transfer your samples to buffer only after
about 48 hours (depending on tissue size)?  I used to keep excess EM
specimens in buffer at 4C for many months without apparent tissue damage.  

	If you are considering serious long term storage, ie years before
embedding, then transfering the tissue to a museum mounting fluid may be
appropriate.  For long storage times you need to consider the pH capacity
of your buffer, most long term buffers are phosphate based.

	However, you should be able to store your sample for several weeks if not
a couple of months in fixative without serious problems, bearing in mind my
opening statement.

	Regards
	
	Rob.

At 09:08 AM 7/12/99 -0600, you wrote:
>We are going to be embedding rat lung tissue in GMA . How long can you store
>the tissue in a fixative of paraformaldehyde 1% gluteraldehyde in a
>phosphate buffer?  
>Thanks
>Jennifer
>Jennifer Berger
>Lovelace Respiratory Research Institute
>Albuquerque, NM
>jberger@lrri.org


R. Wadley, B.App.Sc, M.L.S
Laboratory Manager
Cellular Analysis Facility
School of Microbiology & Immunology
UNSW, New South Wales, Australia, 2052
Ph (BH) 	+61 (2) 9385 3517
Ph (AH)	+61 (2) 9555 1239
Fax 	+61 (2) 9385 1591
E-mail	r.wadley@unsw.edu.au
www	http://www.micro.unsw.edu.au/caf.html