[Histonet] Can use some help with processing references

[Ingles Claire]

We have also removed the blocks and let them harden until we are ready to embed them, then put back in the hot well on the embedder to warm back up and go from there. As they are already processed and 
infiltrated, I don't think there would be a problem leaving them at room temperature for a few days.
Claire

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From: histonet-bounces <@t> lists.utsouthwestern.edu on behalf of Ian R Bernard
Sent: Sun 5/13/2012 4:48 PM
To: Jackie O'Connor; histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] Can use some help with processing references



Rather than research literature (lit), may I refer you to the foremost authority on histotechnology procedures: Histotechonology- A Self Instructional Text, 3rd Edition by Frieda Carson and Christa Hladik, Chapter 2, page 38, paragraph 2: "Tissue should remain in paraffin the shortest time necessary for good infiltration because exposure to prolonged heat causes shrinkage and hardening."  I consider book the foremost (bible) reference on histotechnology.  At least I hope so, since I'm studying for my HTL from this book. Note: There are lit at the end of this chapter that may go into more detail.

The paragraph goes on to state that: " ...melted paraffin should be kept 2 to 4 degrees Celsius above the melting point because tissues exposed to overheated paraffin during infiltration will over harden.

Bottom-line, I would not leave tissues in paraffin over the weekend.  If you are using an automatic-closed system processor, your equipment should be able to work on a delayed status, where the tissues will sit in 10 Neutral Buffered Formalin under vacuum (better for the tissue), all weekend, and start processing schedule on Sunday to come off on Monday morning. At least ours does.

Hope this helps.

Ian R. Bernard
Ian R. Bernard, MSHA, HT (ASCP)
10th Medical Group- Anatomic Pathology Lab
USAF Academy, CO 80840



-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Jackie O'Connor
Sent: Sunday, May 13, 2012 2:42 PM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Can use some help with processing references



Hi Y'all - I'm kind of in a jam here - I'm looking for references on paraffin tissue processing - can someone point me towards any literature that says leaving tissues in molten paraffin over the weekend is a bad idea?  I need to prove a point, and need something to back me up.  I'm out of the US doing a consult, having trouble doing a lit search - I'm really not lazy. 
Thanks in advance.
Jackie O'
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