[Histonet] Soaking artifact

Mon Jan 6 08:54:06 CST 2014

Thanks Peggy and Amen!  When you have people taking human tissue and facing 25 or 30 blocks at a time and then leaving them face down on ice with water it causes the issues you stated.  Soaking is something that was far more common in the past as the tissue fixed on processors with less reagent (Technicons Monos, Duos and Ultras) and did not always come out well processed.  The fact that we would throw everything, no matter the size from tiny biopsies to huge hunks of tissue in was normal practice.  

We follow the practice the person is complaining about and only soaking for tissue with special requirements, such as bloody.  Everyone hated till they tried and realized it works better.  The pathologists are happier as the tissue is not water logged and stains better.

We have come a long way in the last 48 years I have been doing Histology and we need look at some old practices and update.  Lee did say rehydrate however; he also said be careful and do not allow the tissue to swell out of the block.  

Pam Marcum
UAMS

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Lee & Peggy Wenk
Sent: Monday, January 06, 2014 7:34 AM
To: Deanna Leslie; histonet <@t> lists.utsouthwestern.edu
Subject: Re: [Histonet] Soaking artifact

One slight amendment - this applies to human tissue.

Animal tissue has far less bound and unbound water to start with, so no matter how it's processed, it always ends up "dry". Therefore, longer soaking in water is needed.

Peggy A. Wenk, HTL(ASCP)SLS

-----Original Message-----
From: Lee & Peggy Wenk
Sent: Monday, January 06, 2014 8:07 AM
To: Deanna Leslie ; histonet <@t> lists.utsouthwestern.edu
Subject: Re: [Histonet] Soaking artifact

The only "soaking" artifacts that I can think of would be caused by:
- soaking too long in water (minutes instead of a few seconds)
- soaking under-processed tissue in water

In both cases, the tissue is supposed to be "protected" by the wax, and if it is not (under-processed), or if the faced block is in water too long, the tissue can start re-absorbing water. The tissue then turns white and swells out of the block. So all that "swelled out" tissue is cut away and lost when the tissue is put back on the microtomy for sectioning the ribbon.

If you soak for just a few seconds, such as a gauze with water being held against the block on the microtome, after it has been faced, then you will get a little bit of water absorbed into just a few layers of cells. Just enough to cut 2-4 sections. And you won't see that swelling artifact.

For those of you saying - "but I have to face all the blocks, put them back on ice and/or water while I cut a bunch more blocks, and then go back and cut each block" - that is an artifact also. You have over-dehydrated your tissue during processing, and you are putting back the water that you should not have taken out. Processing is supposed to remove the unbound water (not attached to proteins), and some of the bound water (attached to proteins), and leave some of the bound water (attached to proteins) in the tissue. If you HAVE to soak EVERY block for more than a couple of seconds, then you are wasting time rehydrating and wasting time while microtoming. Cut down the time in the alcohols on the tissue processor, to leave a little bound water in the tissues. And you can NOT processing little biopsies on the same long processing cycle as the larger pieces of tissue (uterus, breast, etc.).
Those little biopsies will be over-dehydrated. They HAVE to be run on a separate cycle of much shorter time intervals (10-20 minutes in each solution (once fixed), instead of 45-60 minutes in each solution).

You should be able (on nearly every tissue block) to rough trim the tissue, and immediately start cutting ribbons. Possibly, you will need to put an ice cube on some of the harder tissue (cervix, uterus, bone, lens, etc.) just to get the paraffin hardness to match the hardness of the tissue. That being said, some tissues are naturally brittle or crumbly, and always need some water put back in the tissue, such as spleen or bloody tissue, but again, some wet gauze on the faced block for a few seconds should be enough time to get 2-4 sections. And that's all the tissue we usually need from those blocks. If you need more for IHC, put the wet gauze back on the faced block, and cut a few more sections.

Peggy A. Wenk, HTL(ASCP)SLS

-----Original Message-----
From: Deanna Leslie
Sent: Sunday, January 05, 2014 4:42 PM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Soaking artifact

Has anybody in histoland ever heard of this?  I have been cutting tissue for 25 yrs and until recently I had never heard of this!
I am under contract to a facility and the supervisor there does not want anybody to soak their tissue or use ice!  Your are supposed to use the cold plate, because as I have stated soaking them causing an artifact. I have not disputed this because it is not my place or in my job discription as a traveler.  I am not even sure what it is supposed to look like or what type of problems it causes.

Thanks for listening!
Deanna Leslie HT ASCP
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