[Histonet] TEM for paraffin embedded tissue section??

Morken, Tim tim.morken <@t> thermofisher.com
Mon Jan 15 10:33:00 CST 2007

 Ul Soo Choi,

Here is a method perfect for your need to see neurosecretory granules.

You can skip all the reprocessing from paraffin to EM resin by using 1
percent osmium in xylene to deparaffinize. This was pioneered by Kai
Chien of Cedars-Sinai in Los Angeles. 

1) Cut paraffin tissue in 1mm cubes.
2) deparaffinize in 1 percent osmium in xylene for several changes.
3) Clear in pure xylene
4) Infiltrate in a xylene/resin mix for several changes.
5) Infiltrate in pure resin
6) embed

This will save hours and many of those tedious solution changes.

The morphology isn't the great (or even good!) compared to standard EM methods, but it is useful for distinguishing lymphomas from carcinomas
(lack of or presence of desmosomes), finding neurosecretory granuals in
carcinoids and pre-melanosomes in melanomas. It is really only useful as
a last attempt to get information after the specimen was wrongly
submitted and all other tests fail to give answers.

Chien, K, R.L. Van de Velde, R.C. Heusser, 1982, A one-step method for re-embedding paraffin-embedded specimens for electron microscopey, p.356-357, Proceedings fo the Electron Microscopy Society of America, 40th Annual Meeting, San Francisco Press, Inc, San Francisco, CA.

Tim Morken
Technical Support Manager
Lab Vision - Neomarkers
ThermoFisher Scientific

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Choi Ul Soo
Sent: Sunday, January 14, 2007 9:55 PM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] TEM for paraffin embedded tissue section??

Hello Dear Histonetters!

would anyone there tell me the story about using paraffin embedded tissue section for TEM analysis? 
I have seen several reports reading that they used paraffin embedded tissues for transmisison electron microscopy, but our technician is not familiar to this method. 

Would the results be consistent regardless of the objects of interest, fixation or tissues? I'd like to get findings indicative of neuroendocrine origins from a canine lung mass fixed in formalin, and paraffin embedded tisse section. 

Please share your experiences and give me advice. 

Any inputs would be very much appreciated. 

Ul Soo Choi
VMTH 208, CVM, Seoul National University, Shilim9 dong, Gwanakgu, Seoul, Korea 151-742 Tel. 82-02-880-8688 Mobile. 82-016-9228-8634 Fax. 82-02-880-8662

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