SV: [Histonet] How to store paraffin blocks ?

[Erikstad, Gudrun Hovstein]

 Hi,

We store paraffin blocks and stained slides at room temperature in rooms without windows, so there is no sunlight.
We store blocks and slides "forever". We have paraffin blocks from before 1930.
"Room temperature" in Norway is usually about 20 degrees Celcius.

Some stained slides will fade with time (silver techniques, immuno), but the routine HE usually last for many, many years.
After we excanged Xylene with a substitute (Tissue-Clear) four years ago, we had some "bleeding" and fading of the HE-stains, but after taking more care changing the Xylene substitute in the clearing step more often this is no more a problem.
The paraffin blocks keep very well. We frequently do section and stain as well as do molecular techniques (PCR, In situ) on material from the 1970'ies and before, and it's remarkable how well the formalin fixed, paraffin embedded tissue keep.

I would not keep the blocks in a fridge, as you say, the humidity in the fridge is quite high.
The time to cool a block from room temperature to suitable for sectioning is only about two minutes.
Now, because Norway has a relatively cold climate, the air humidity is also quite low compared to warmer climates, even if it rains here ALL the time... ;-)
Heat and high humidity might affect your blocks.

Gudrun H. Erikstad, Trondheim, Norway



-----Opprinnelig melding-----
Fra: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] På vegne av Itai Moshe
Sendt: 20. september 2011 08:23
Til: histonet <@t> lists.utsouthwestern.edu
Emne: [Histonet] How to store paraffin blocks ?

Hi Histonet's,

What is the recommended way to store paraffin blocks for a long period ?
Room temperature, or 4C ?

The advantage in storing at 4C is that the blocks are always ready for sectioning.
Is there a risk when storing at 4C that the humidity in the fridge will cause damage to the paraffin blocks and the tissue ?
After sectioning, How do you store the slides, and for how long ?


Thank's
Itai Moshe
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