What are Artifacts in Histology?
Artifacts are extraneous, misleading structures or alterations that appear in histological sections but were not present in the original tissue. These anomalies can obscure the accurate interpretation of tissue morphology and cellular details, potentially leading to diagnostic errors.
Common Sources of Artifacts
Artifacts can arise from various stages of sample preparation, including
fixation,
dehydration,
embedding, sectioning, and staining. Understanding these sources is crucial for minimizing their impact.
Fixation Artifacts
Fixatives like formaldehyde are essential for preserving tissue morphology and preventing degradation. However, improper fixation can lead to artifacts. For example, delayed fixation may cause tissue autolysis, while over-fixation can lead to hardening and shrinkage.
Dehydration and Clearing Artifacts
During dehydration, tissues are passed through a series of alcohol baths. If the process is too rapid, it can cause tissue shrinkage and distortion. Inadequate clearing, which involves replacing alcohol with a substance like xylene, can result in incomplete removal of alcohol, causing tissue opacity.Embedding Artifacts
Embedding tissues in paraffin or other media is a delicate process. Improper orientation, incomplete infiltration, or air bubbles can introduce artifacts. Overheating the paraffin can also cause tissue shrinkage and hardening.
Sectioning Artifacts
Microtome sectioning can introduce artifacts such as chatter (alternating thick and thin sections), knife marks, and compression. Properly maintaining the microtome blade and adjusting cutting speed can minimize these issues.Staining Artifacts
Staining procedures, crucial for visualizing tissue structures, can also introduce artifacts. Overstaining or understaining can obscure cellular details. Inconsistent staining may result from uneven reagent application or improper timing.
Identifying and Minimizing Artifacts
Being able to recognize and distinguish artifacts from true histological structures is essential. Implementing rigorous QC protocols, such as standardizing fixation times and reagents, can help reduce artifact generation. Regular maintenance of equipment like microtomes and adherence to standardized staining protocols are also beneficial.Common Types of Artifacts
Some common artifacts include:
- Folding: Sections may fold during mounting, leading to overlapping tissue layers.
- Air Bubbles: Can be introduced during mounting and can obscure tissue details.
- Chatter: Alternating thick and thin sections caused by a dull microtome blade.
- Knife Marks: Streaks caused by nicks or imperfections in the microtome blade.
- Shrinkage: Tissue shrinkage due to over-fixation or rapid dehydration.Conclusion
Artifacts are an inevitable part of
histological examinations, but understanding their sources and types can greatly aid in minimizing their impact. Careful attention to each step of the tissue preparation process, from fixation to staining, is crucial for reducing the introduction of artifacts and ensuring accurate tissue analysis.
