Author: Peggy A. Wenk, BA, BS, HTL(ASCP)SLS The anti-roll plate is a square or rectangle of plastic or glass that rests against the blade in the cryostat, and allows the tissue to slide between the anti-roll plate and the knife. This allows for flatter sections, which can be picked up on the slide with fewer wrinkles, IF the anti-roll plate is behaving properly.
First, check to make sure the poor sections are not due to something else, such as a dull blade or a wrong clearance angle. If you can get a fairly good section without the anti-roll plate, then let’s look at three common problems that occur with the anti-roll plate.
Just so we know which side of the anti-roll plate I’m talking about, imagine a square (or rectangle) shape. North side is touching the blade. East and West sides are the vertical edges.
The entire North length of the anti-roll plate does not lay flat against the blade. Only a couple of millimeters of the East and West sides are touching the blades. That is because the East and West sides are thicker. This allows the majority of the middle portion of the North side to be raised off the blade a fraction of a millimeter. This gap lets the section slide between the anti-roll plate and the blade, but does not permit too much space to allow waviness of the section.
If you are cutting thick sections, they may be thicker than the gap between the plate and the blade. The section will jam up against the top of the anti-roll plate. To increase the gap thickness, wrap cellophane tape around the East and West edges, raising the middle section off the blade a fraction of a millimeter.
JAGGED EDGE OF ANTI-ROLL PLATE:
If the North edge of the anti-roll plate that is lying against the blade has been damaged by having something hit it, such as ice, something hard in the tissue, or being hit by the chuck that was not far enough back, then the anti-roll plate will have a jagged edge in a spot or two. This jagged spot or spots will grab the tissue, and snag it. Buy a new anti-roll plate and replace the old one. Or, try taking out the old one, and sanding the jagged edge on an Emory board, first the coarse side, and then the fine. Reattach the old anti-roll plate, and see if that sanding took care of the problem. Money saved!
Possibly what is causing the anti-roll plate North edge to be jagged is some debris on the edge, such as ice, old tissue, or frozen OCT. Wipe off the edge with cold gauze, so as not to heat up the plate with room-temperature gauze, if you were planning on sectioning right away. Remember to watch where your fingers are in relation to the knife edge. You might want to remove the blade while doing this step.
ANTI-ROLL PLATE POSITION:
The North edge of the anti-roll plate should be a ¼ to a ½ mm in front of the edge of the blade. It should look like the anti-roll plate is sticking out longer than the knife edge. Start with the anti-roll plate and the knife edge being parallel. Move the anti-roll plate up (out) a hair’s width. Try to obtain a section. If that doesn’t work, move the anti-roll plate up (out) another hairs’ width. Keep advancing the plate and trying to get a section, until you get the correct distance. If the anti-roll plate if too far forward, the OCT block or chuck will hit the edge of the plate. If the plate isn’t quite forward enough, you won’t get a section under the plate. If the plate is too far down, the tissue will roll up on the edge of the anti-roll plate.
It’s like the baby bear in Goldilocks – it has to be just right.