Microtome Cutting Tips: How Can I Resolve Thick & Thin Sections?

Microtome Cutting Tips

Welcome to our second installment of microtome cutting tips where we explore common sectioning issues and solutions to them. Below we explore the causes and solutions to a common microtome cutting issue– thick and thin sections.

What Causes Thick & Thin Sections?

Thick & Thin Sections can occur due to the following:

• Too little knife/blade tilt – clearance angle too small. Bottom rather than the top of the blade facet contacts the block. This results in compression of the tissue. However, with continued advancement the top of the blade edge finally contacts the block and a section is cut.
• This alternating compression and sectioning of the block yields “skipped” and “thick sections.”
• Loose: block holder/ blade pressure plate/clamping set screws and levers.
• Worn microtome parts/microtome out of calibration.
• Sectioning very dense tissue (ex. Uterus).
• Pressure plate tightened too much resulting in a bowing of the disposable blade.
• Residual paraffin on block edges- preventing adequate tightening of the block in the specimen clamp.

Microtome Cutting Tips

Welcome to our second installment of microtome cutting tips where we explore common sectioning issues and solutions to them. Below we explore the causes and solutions to a common microtome cutting issue– thick and thin sections.

What Causes Thick & Thin Sections?

Thick & Thin Sections can occur due to the following:

• Too little knife/blade tilt – clearance angle too small. Bottom rather than the top of the blade facet contacts the block. This results in compression of the tissue. However, with continued advancement the top of the blade edge finally contacts the block and a section is cut.
• This alternating compression and sectioning of the block yields “skipped” and “thick sections.”
• Loose: block holder/ blade pressure plate/clamping set screws and levers.
• Worn microtome parts/microtome out of calibration.
• Sectioning very dense tissue (ex. Uterus).
• Pressure plate tightened too much resulting in a bowing of the disposable blade.
• Residual paraffin on block edges- preventing adequate tightening of the block in the specimen clamp.

Solutions to Thick & Thin Sections

• Increase blade tilt / greater clearance angle.
• Tighten set screws, clamps and locking levers. Apply reasonable pressure.  Do not over tighten.
• Microtome out of adjustment, needs calibrated. Schedule preventive maintenance once or twice a year depending on workload.
• Make sure tissue block is firmly held in the specimen clamp and that the back of the tissue cassette is completely filled with paraffin to avoid thick and thin sections.
• Tighten levers just enough to secure blade.
• Trim all paraffin around block edges and top so that the cassette can be clamped with equal pressure from all sides in the specimen clamp.
• Never take the first several sections when fine cutting as these are usually thicker than the actual micrometer setting.

Looking to Purchase a Microtome?

The MES800 Rotary Microtome by Craftek is a reliable manual and semi-automated rotary microtome for routine sectioning of specimens in clinical and research laboratories. This easy to use, state of the art microtome features a quick release specimen clamp, easy exchange specimen clamp, bi-directional course advance switch, and more. As part of our exclusive line of new laboratory equipment, this microtome is a great addition to any pathology lab. Talk to our sales team today about the MES800 microtome!