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<DIV><FONT face=Arial size=2>I am fairly new to histochemical techniques, and
have some tissue storage questions. We are freezing whole rat embryo
heads/brains on the fast freeze shelf of a cryostat set to -35 C. Then we place
the frozen tissue in vac-u-pac bags, and store at -20 C, with the intent of
slicing the specimens within a few months. However, I'm now starting a project
where I may not be able to slice and process the tissue (for cytochrome
oxidase activity in the brain) for about a year. Concerning long term
tissue storage:</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>1. What are the advantages/disadvantages of long
term storage in freezers at -20, versus -40, or -80 C?</FONT> </DIV>
<DIV><FONT face=Arial size=2>2. Because I'm already storing the specimens in
vacuum sealed bags, would freezing & storing in OCT add any benefit? (I
have experienced OCT that has become "gummy" after more than a few days when
stored in a Ziploc bag at -20 C, but haven't tried it with the vacuum sealed
bags.</FONT></DIV>
<DIV><FONT face=Arial size=2>3. Would storage at colder temperatures necessitate
a different freezing protocol (e.g. slower or faster freezing)?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I appreciate any information you can give me on
this subject.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Gale</FONT></DIV></FONT></DIV>
<DIV><FONT face=Arial
size=2>______________________________________________________<BR> <BR>Gale
A. Kleven<BR>Department of Psychology<BR>University of
Iowa
<A
href="http://www.psychology.uiowa.edu/">http://www.psychology.uiowa.edu/</A><BR>E11
Seashore Hall<BR>Iowa City, IA
52246
email: <A
href="mailto:gale-kleven@uiowa.edu">gale-kleven@uiowa.edu</A><BR>______________________________________________________</FONT></DIV></BODY></HTML>