What are Imaging Artifacts?
Imaging artifacts in histology refer to any distortion or error in the visual representation of a tissue sample that does not correspond to the true structure within the tissue. These artifacts can arise from various stages of sample preparation, staining, or imaging processes, and can significantly affect the interpretation of histological data.
Common Causes of Imaging Artifacts
Artifacts can result from several sources, including: Fixation: Inadequate fixation can lead to poor preservation of tissue structure, causing shrinkage, swelling, or other distortions.
Sectioning: Improper sectioning techniques can produce folds, tears, or compression artifacts in tissue sections.
Staining: Uneven or non-specific staining can create misleading color patterns that do not reflect the actual tissue composition.
Mounting: Air bubbles or dust trapped under the cover slip can obscure details in the tissue section.
Microscopy: Poor alignment, lens aberrations, or improper illumination of the microscope can introduce visual distortions.
How to Identify Imaging Artifacts
Identifying artifacts requires a combination of experience and careful examination. Some general tips to spot them include: Look for
repetitive patterns that are unlikely to be biological in origin.
Compare the suspicious areas with known histological structures and patterns.
Use
control samples to distinguish between true tissue features and artifacts.
Consult with colleagues or reference texts to confirm findings.
Types of Common Artifacts
Several types of artifacts are frequently encountered in histology:Fixation Artifacts
Improper fixation can cause several issues, including:
Autolysis: Degradation of tissue due to delayed fixation.
Formalin Pigment: Dark brown deposits resulting from prolonged fixation in formalin.
Shrinkage: Tissue appearing smaller than its actual size due to dehydration or over-fixation.
Sectioning Artifacts
Artifacts related to sectioning include:
Knife Marks: Parallel lines caused by a dull microtome blade.
Compression: Tissue appearing squished due to excessive pressure during sectioning.
Folds and Wrinkles: Overlapping tissue layers that obscure underlying structures.
Staining Artifacts
Errors in the staining process can produce artifacts such as:
Over-staining: Excessive dye leading to too-dark sections that obscure details.
Under-staining: Insufficient dye leading to pale sections that lack contrast.
Non-specific Staining: Stains that bind to unintended structures, causing misleading results.
Mounting Artifacts
Mounting artifacts typically include:
How to Minimize and Prevent Artifacts
Preventing artifacts involves meticulous attention to each step of the histological process: Ensure proper and timely
fixation of tissue samples.
Use well-maintained and sharp microtome blades for sectioning.
Follow standardized
staining protocols and validate each batch of stain.
Carefully mount sections under coverslips to avoid air bubbles and dust.
Regularly calibrate and maintain
microscopy equipment.
Conclusion
Imaging artifacts are a common challenge in histology that can interfere with accurate tissue analysis. By understanding their sources and characteristics, histologists can take steps to identify, minimize, and prevent these artifacts, ensuring more reliable and interpretable results.
