Keep Paraffin Blocks as Cold as Ice

Histological examination is considered the gold standard for detection, diagnosis and characterization of many clinical conditions, and producing suitable sections for microscopic examination constitutes one of the primary skills of the histologist.

Preparing and embedding tissue in a suitable matrix enables the technician to produce sections of an appropriate thickness for pathological analysis.

Paraffin wax continues to be the most popular embedding medium, due to its low cost and ease of use, facilitating long-term storage of the embedded tissue blocks.

To promote good ribbon generation, the paraffin block needs to be sufficiently hard to enable the sections to be cut on the microtome.

This is routinely achieved by placing the paraffin blocks on ice, cooling both the tissue and the wax to a similar consistency and swelling the tissue to make it easier to section.

As the block heats up, however, the paraffin softens and expands, resulting in corrugation and variations in the consistency of the sections, rendering some unsuitable for use.

Technicians therefore have a finite time in which they can section and, as a result, have to continually remove the block from the microtome and re-cool it on ice to achieve the quality of sections required for downstream analysis, impacting workflow and laboratory throughput.

The Thermo Scientific Cool Cut Clamp is a peltier-cooled specimen clamp which helps to address this issue by maintaining the paraffin block at a suitable temperature for sectioning for a prolonged period.

Compatible with all the Thermo Scientific HM range of rotary microtomes, the Thermo Scientific Cool Cut provides laboratories with the ability to achieve consistent section thickness when cutting individual, step and serial sections, with minimal interruptions.

“Students have commented that they find it much easier to achieve good ribboning with the Cool Cut Clamp,” commented Dr Neil Pickles, University of Chester, who uses the Thermo Scientific HM355S Microtome configured with the Cool Cut when training Biomedical Science students in histology techniques.

Dr Pickles continued, “We created a temperature profile to compare the Cool Cut with a standard specimen clamp and established that we can keep the temperature of the block at 8-12°C for more than 5 minutes without having to re-cool it on ice. Having more time to section a block allows students to practice and develop their microtomy skills much more rapidly.”