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The page below is a sample from the LabCE course Microtomy of Paraffin-Embedded Tissue. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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Microtomy Artifacts: Causes and Corrections

The summary below examines the most common microtomy artifacts that can be seen under the microscope when viewing stained tissue sections. Some types of tissue are more prone to certain kinds of artifacts. Identifying which tissues will lead to certain artifacts will allow for preventive measures rather than corrective actions.
Chatter and micro-vibration: Parallel tears or fractures in tissue (shown in the upper image); some tissue may be splintering out (shattering)
  • Tissues: Intestine, liver, lymph node, bloody tissue, spleen, and brain
  • Causes: Over-dehydrated tissue, dull knife, clearance angle too wide, cutting too rapidly, or vibration in microtome parts
  • Correction: Adjust processing cycle to reduce time in alcohols, soak blocks in ice water before sectioning, use new blade, adjust clearance angle, cut at one revolution per second, clamp down all microtome parts
Thick/thin areas, "venetian blinds", washboarding, undulations, and skipping: Parallel undulations (shown in the lower image) of varied thickness
  • Tissues: Any tissue, particularly dense and hard tissues, and tissue with various densities, including bone, uterus, and brain
  • Cause: Tissue may be overly dehydrated, over-hardened, not secure in the paraffin block; blade may not be secure, vibrations in microtome, rapid sectioning, block loose in block holder, dull knife, or clearance angle too wide
  • Correction: Adjust processing cycle to decrease dehydration, soak blocks in water before sectioning, re-embed tissue in new paraffin, use new knife, clamp down all microtome parts, adjust clearance angle, or slow down sectioning
Folds and wrinkles: Folding or over-lapping of tissue cells
  • Tissue: Any tissue, particularly skin and tissue with various layers of elastic and collagen tissue elements, such as intestine
  • Cause: Poor technique of laying ribbon on water, not enough stretching or manipulation of sections, not enough time on water, water bath temperature too cool, not enough slide drying time, or poor tissue adhesion
  • Correction: Adjust water temperature of water bath, stretch ribbon as it is laid on water surface, gently stretch sections, give ample time for sections to relax on water, increase slide drying time, and use charged slides or adhesives
"Moth-eaten" and irregular holes: Missing tissue in parallel pattern, oblong and irregular holes, parts of tissue are chunked out
  • Tissue: Any tissue, particularly uterus, liver, spleen, and brain
  • Cause: Aggressive block facing and trimming, microns too high for trimming, trimming too rapid, knife not locked down properly, or dull knife
  • Correction: Decrease microns for coarse facing, slow down, tighten blade down, use new blade, and be sure to section through holes until block surface is free of holes