[Histonet] Tissue left in processor

[gayle callis]

Some prefer to take the cassettes off the processor and let them harden
until embedding can be done, rather than leave in molten, hot paraffin.
This does not damage the tissue, and placing the cooled cassettes into the
embedding center holding area allows the paraffin to re-melt in a shorter
time before embedding.  This has been discussed in the past on Histonet.
Some tissues may dry out even more WITH difficult sectioning after prolonged
heat exposure.  One result will be a parched earth effect seen in sections.
I see you are from a veterinary facility, and if you work with rodent
tissues e.g. spleen and liver, you should not let the tissue sit in paraffin
or you will have little hard rocks to section.    If your sectioning suffers
(dry, friable, shattered, hard)  after allowing tissues to sit in hot
paraffin as compared to the times when you embed asap after processing is
finished, then over exposure to hot paraffin can contributing factor.   

I personally do not like to "cook" my tissue any longer than necessary and
heat labile antigens will also be at risk.  I schedule so I can be there to
embed when the processing is completed.     

Our standard is to embed when processing is finished and schedule
accordingly.      

Gayle Callis
HTL/HT/MT(ASCP)    

   

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Janice
Mahoney
Sent: Thursday, October 06, 2011 9:45 AM
To: rjbuesa <@t> yahoo.com; histo net; rcharles <@t> pa.gov
Subject: RE: [Histonet] Tissue left in processor


I agree with Rene, as long as the temp is only a few degrees above the
melting point of the paraffin.Jan,Omaha

> Date: Thu, 6 Oct 2011 07:13:54 -0700
> From: rjbuesa <@t> yahoo.com
> To: histonet <@t> lists.utsouthwestern.edu; rcharles <@t> pa.gov
> Subject: Re: [Histonet] Tissue left in processor
> CC: 
> 
> I do not think that a well fixed, well processed tissue left in molten
paraffin for 2 hours after the processor finished will have any adverse
outcome.
> René J.
> 
> --- On Thu, 10/6/11, Charles, Roger <rcharles <@t> pa.gov> wrote:
> 
> 
> From: Charles, Roger <rcharles <@t> pa.gov>
> Subject: [Histonet] Tissue left in processor
> To: "Histonet (histonet <@t> lists.utsouthwestern.edu)" 
> <histonet <@t> lists.utsouthwestern.edu>
> Date: Thursday, October 6, 2011, 10:05 AM
> 
> 
> Hi All,
> Is there any standard on how long tissue cassettes can remain in the
processor after processing before the tissue is subjected to unwanted
outcomes?  And if so  what type of artifacts can one expect from tissue that
was in the processor in molten paraffin for 2 hours after the processing was
completed?
> Thanks so much.
> Roger
> 
> Roger Charles| Microbiologist II
> Pennsylvania Veterinary Laboratory
> 2305 North Cameron Street | Harrisburg, PA 17110
> Phone: 717.787.8808 | Fax: 717.772.3895 
> www.agriculture.state.pa.us<http://www.agriculture.state.pa.us>