What are Artifacts in Histology?
Artifacts in histology are any structures or features that appear in tissue sections but are not present in the living organism. These anomalies can arise during tissue preparation, fixation, embedding, sectioning, or staining and can potentially lead to misinterpretation of the tissue's true histological architecture.
Common Types of Artifacts
There are several types of artifacts that can occur during histological processing, including: Folding: Tissue sections may fold over themselves, creating artificial layers or duplications.
Air Bubbles: Air trapped under the coverslip can create round, empty spaces that may be mistaken for cellular structures.
Knife Marks: These are linear scratches caused by imperfections in the microtome blade.
Shrinkage: Tissue may shrink during dehydration and embedding, causing gaps and distortions.
Staining Artifacts: Uneven staining or precipitates can obscure cellular details or mimic pathological changes.
How to Recognize Artifacts
Recognizing artifacts is a critical skill for histologists and pathologists. Here are some tips: Consistency: Artifacts often appear consistently across multiple sections or slides, whereas genuine structures are variable.
Location: Artifacts may be localized to certain areas, such as the edges of the tissue section or near the coverslip.
Shape: Regular, geometric shapes are more likely to be artifacts, whereas biological structures tend to be irregular and complex.
Context: Compare with known histological features and consider the overall tissue architecture.
Prevention and Minimization
While some level of artifact formation is inevitable, there are steps that can be taken to minimize their occurrence: Proper Fixation: Ensuring adequate fixation time and using the correct fixative can reduce many artifacts.
Careful Sectioning: Using a sharp microtome blade and cutting at the appropriate thickness can prevent folding and knife marks.
Dehydration: Gradual dehydration through alcohol gradients can minimize shrinkage artifacts.
Staining Techniques: Following established protocols and avoiding over or under staining can prevent staining artifacts.
Case Studies
Let's explore a couple of case studies to illustrate artifact recognition:
Case Study 1: Mistaken Identity
A pathologist observed what appeared to be large, round cells in a liver biopsy. Upon closer examination, the cells were found to be air bubbles trapped during mounting, not pathological changes.Case Study 2: Shrinkage Confusion
In a muscle biopsy, gaps between muscle fibers were initially thought to indicate tissue damage. However, it was determined that these gaps resulted from shrinkage during dehydration, not a pathological process.
Advanced Techniques
With advancements in imaging and tissue preparation, newer techniques can help differentiate between artifacts and true histological features: Digital Pathology: High-resolution digital imaging allows for better visualization and identification of artifacts.
Immunohistochemistry: Using specific antibodies can highlight genuine cellular structures, helping to distinguish them from artifacts.
Confocal Microscopy: This technique provides clearer, three-dimensional images that can help differentiate between artifacts and actual tissue features.
Conclusion
Artifact recognition is a fundamental skill in histology that requires careful attention to detail and a thorough understanding of tissue processing techniques. By recognizing and minimizing artifacts, histologists and pathologists can ensure accurate interpretation of histological specimens, leading to better diagnostic outcomes.
