RE: wierd artifact on tissue

From:Gary Gill

You can test for the presence of incompletely removed paraffin by examining "deparaffinized" unstained sections between crossed polarizing filters (i.e., one below the microscope stage [e.g., on top of the blue filter] and the other one above the specimen [e.g., sitting on top of the wet coverslipped section]).  Rotate one filter only until the field-of-view becomes dark.  Any residual paraffin will rotate the polarized light and appear white, since the paraffin is allowing light to be transmitted through those areas of the sections.  To fully appreciate the effect, first use a section that has not been through xylene.
Historically, some authors have pointed out that there is always some residual paraffin, but not enough to be problematical in routine applications.  Wiith the advent of image analysis techniques many years ago, which are sensitive to residual paraffin, complete deparaffinization can be accomplished by dewaxing the sections twice (i.e., immerse in xylene per routine, rinse in alcohol down to water, back up to alcohol, and then through a second set of xylene baths).
Synthetic waxes also rotate polarized light.
Gary Gill
-----Original Message-----
From: []
Sent: Friday, December 06, 2002 12:16 PM
Subject: FW: wierd artifact on tissue

We experienced a similar problem and it was identified by a pathologist as inadequate removal of wax during the staining process. This can be caused by the xylene not dissolving out the wax properly. Check the times on your staining machine. Alternatively the machine is not being changed often enough.
Rita Russell
-----Original Message-----
From: []
Sent: 04 December 2002 23:03
Subject: wierd artifact on tissue

Hello all. I could really use some help. Today, the pathologist called to say that she is seeing an artifact on the tissue. It looks like clusters of fine PCP organisms, only that they are not. Like someone took a very fine tip black marker and made circles around the cells. She said it is not on every slide. The slides she had me check were prostate needle bx's and an antrum bx. The only change in our routine has been that we are demonstrating a recycling system for alcohol and Xylene. I have not used the recycled product on the tissue processor or the H&E autostainer, but I have placed the recycled Xylene in our glass Coverslipper.

I appreciate any and all comments.
Thank you.
Allan Memorial

<< Previous Message | Next Message >>