Slicing sections of tissues is a routine application in histology. Cryostat sectioning is one of the best methods to accomplish this. If not done properly, it can simply cause the tissue to melt, fold, curl, crack, or tear. We will address how to avoid tears. Tearing can occur if your blade is too dull or dirty, your damaged lead anti-roll plate needs replacement, or the temperature of your working environment is too low.
Main reasons sections tear as they are being cut?
- The blade/knife edge is blunt or there is dirt, dust, frost or rust on the edge.
- The leading edge of the anti-roll plate is damaged. Replace the plate.
- The back of the blade back is dirty. Clean, or replace the blade.
- The temperature is too low for the tissue to be cut.
A dull or used blade will cause the tissue to tear perpendicular to the blade. Try cleaning the blade of any dirt, dust, frost or rust. If this does not correct the problem, then replace the blade. Ensure that the block and knife blade are clamped tight.
Increase (raise) the temperature, wait a few minutes and try sectioning again.
Rough cut the block with one end of the blade, then move to the unused portion of the blade to take your sections.
Tears parallel to the blade may be chatter which is caused by something loose. Make sure the block and knife are clamped tight. The OCT can also come loose from the chuck and will need to be remounted.
First of all, though, there is the problem of non-observant histologist not even seeing the tear in the first place. Tears on desired sections can be notoriously hard to detect. That is why there should be an automated tear algorithm present. There is more than one helpful algorithm present; the more you have in your possession, the merrier. It is fortunate, however, that it is not the end of the world in the event a tear does occur. You can easily seek these fixes out from the experts. Many, but not all, of these fixes while work best on tears that are horizontal and smooth. Most of the time the tears that you will find in coronal tissue are like this.
In any kind of tissue and in a tear of any nature, a tear or tears can stretch too far the tissue on either side of it. Since that is the case, you will want to be extremely careful when trying to repair it. There are specific steps in the reparation process: First, target the area of the primary tear that you are repairing; second, calculate a smooth tear outline; and three, apply one of your algorithms to the tissue in order to begin the repairing. The algorithm should effectively bring the two sides of the tear together.
While it is fortunate that these tears can be fixed, it is unfortunate that the process of fixing them can warp the image. You can avoid this happening by limiting the change in shift from one column to the next while you are in the act of reparation. The outline that is formed can be smoothed down so that it is barely seen. It should be noted that done carefully and with proper care, tears in cryostat sectioning can and should be completely avoided.