Hi Even if you store frozen blocks and sections in a freezer no matter what temperature (even to storing in liquid nitrogen) tissues can still dry out and show various artifacts. This occurs more rapidly with minus 20 than when storing at lower temperatures. Also some freezers automatically defrost, assume your does not. Might I suggest that you check to ensure your freezer does not defrost, and in any case store your sections in a closed container with a few ice cubes - not in contact with tissues of course, this will prevent them drying out. As you note, artifacts cam also be introduced with the initial freezing, depending on the method of freezing, tissue thickness etc. Barry
________________________________________ From: histonet-boun...@lists.utsouthwestern.edu [histonet-boun...@lists.utsouthwestern.edu] On Behalf Of histopath...@gmail.com [histopath...@gmail.com] Sent: Friday, October 21, 2011 8:43 AM To: Histonet@lists.utsouthwestern.edu Subject: [Histonet] ? on frozen tissue artifacts I work in a reference lab and some of our frozen sections exhibit severe freeze artifact (ice crystals). The client claims it's something we're doing and we say they are not freezing them properly. We receive the specimens on dry ice and store them in a -20C freezer until we section them (no more than 1-2 days later). We never allow the tissues to thaw. My question: Can freeze artifact occur AFTER properly snap-freezing tissue or does this artifact ONLY occur during the initial preezing procedure? _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet
