Routine tissue is cut at 3-5 µ, typically one cell thick, one section per slide, one slide per block. Biopsy tissue is usually cut 2-3 µ, a few sections per slide, 2-3 slides per block. Unstained slides are requested when stains are ordered. Cut the unstained slides (at appropriate microns) according to the stain ordered or tissue type.
The table below lists some tissue types requiring tissue section thickness considerations:
Brain and central nervous system (CNS) tissue
- 8-10 µ
- Requires much thicker sections to show neurons
|Tissue for amyloid diagnosis employing Congo red stain |
|Renal (kidney) biopsies|
Special sectioning protocols
Certain tissues have special cutting protocols, including:
- Levels: Most common for biopsies, there can be 2-5 levels per block, used to evaluate various planes of tissue.
- Typically, one level equals 8-10 sections of tissue, however each histotechnologist must use their own judgment/discretion when sectioning levels.
- Levels can be collected initially or as a recut request.
- Block is faced and one ribbon of 10 sections is cut. The FIRST and LAST sections of ribbon are taken for the first two levels and the 8 sections in between are discarded.
- Another ribbon is cut and the last sections are taken for the third level. The rest of the ribbon is discarded.
- Repeat until all levels requested are collected from single block.
- Deepers: Common for skin biopsies. Used to seek out certain tissue elements, like cancer cells.
- A deeper section is collected usually as a recut request.
- Once tissue is faced and ribboned initially. It will be sectioned again to reveal tissue after 20-30 sections and collected again. A full ribbon is discarded between the collections.
- Serial sectioning: Common for biopsies, especially for the diagnosis of Hirschsprung's disease.
- Tissue is minimally faced to reveal the first few cells.
- Consecutive sections must be collected without losing any tissue sections in between ribbons.
- Up to 10 sections are placed on one slide.
- About 300-400 “snap shots” are collected to reveal the tissue in its entirety.
- Very difficult and time consuming.