Specimen Handling - Histology

Why is Proper Specimen Handling Important?

Proper specimen handling is crucial in histology to ensure the accuracy and reliability of diagnostic results. Improper handling can lead to artifacts, tissue degradation, and loss of important cellular details, which can compromise the integrity of the specimen and lead to misdiagnosis.

What are the Key Steps in Specimen Collection?

Specimen collection must be performed with precision. The key steps include:

Identification: Properly label the specimen with patient information and collection details.
Aseptic technique: Use sterile instruments and containers to prevent contamination.
Immediate fixation: Fix the specimen as soon as possible to preserve tissue architecture and cellular details.

How Should Specimens be Transported?

Specimens should be transported in leak-proof, properly labeled containers. They should be kept at an appropriate temperature to prevent degradation. For instance, formalin-fixed specimens should be maintained at room temperature, whereas fresh or unfixed specimens might require refrigeration.

What are the Fixation Techniques Used in Histology?

Fixation is a critical step in preserving tissue morphology. Common fixation techniques include:

Chemical fixation: Using agents like formalin, alcohol, or gluteraldehyde to stabilize tissue structure.
Physical fixation: Methods such as freezing, which is often used for rapid diagnosis in cryosectioning.

What is the Role of Embedding in Specimen Preparation?

Embedding is the process of surrounding the tissue with a solid medium to provide support during sectioning. Common embedding media include paraffin wax for routine histological examination and resins for electron microscopy. Proper embedding ensures that thin sections can be cut without distortion.

How are Specimens Sectioned for Microscopic Examination?

The sectioning of specimens is performed using a microtome. Thin sections, typically 4-6 micrometers thick, are cut from the embedded tissue. These sections are then mounted on glass slides for staining and examination under a microscope.

What Staining Methods are Commonly Used?

Staining enhances the contrast between different tissue components, making cellular structures more visible. Common staining methods include:

Hematoxylin and Eosin (H&E): The most widely used stain in histology, providing good contrast between nuclei and cytoplasm.
Special stains: Such as Periodic Acid-Schiff (PAS), which highlights carbohydrates, or Masson's Trichrome for connective tissue.
Immunohistochemistry: Uses antibodies to detect specific antigens in tissues, providing more precise diagnostic information.

What Are the Common Artifacts in Histology and How to Prevent Them?

Artifacts are distortions or alterations in tissue appearance that can complicate diagnosis. Common artifacts include:

Fixation artifacts: Caused by improper fixation, leading to shrinkage or swelling.
Sectioning artifacts: Tears or folds in tissue sections, often due to blunt microtome blades.
Staining artifacts: Uneven staining or precipitate formation, often due to poor technique or reagent quality.

Preventing artifacts involves following standardized protocols, using high-quality reagents, and maintaining equipment properly.

How is Quality Control Managed in Histology?

Quality control in histology ensures that all procedures produce reliable and accurate results. This involves:

Regular maintenance and calibration of equipment.
Adherence to standardized protocols for specimen handling, processing, and staining.
Continuous training and assessment of technical staff.