What is Histology?
Histology is the study of the microscopic structure of tissues. It involves the examination of tissue sections under a microscope to understand the architecture and function of various biological tissues. Proper technique in histology is crucial to obtaining accurate and reliable results.
Why is Tissue Preparation Important?
Tissue preparation is a fundamental step in histology that includes
fixation, processing, embedding, sectioning, and staining. Each step must be meticulously performed to preserve the tissue's structure and to ensure clear visualization under the microscope.
How to Perform Fixation?
Fixation is the process of preserving tissue samples using chemical agents. It prevents decay and maintains the tissue's cellular structure. Common fixatives include
formaldehyde and
glutaraldehyde. The key to successful fixation is choosing the right fixative and using it for the appropriate duration.
Dehydration: Removal of water from the tissue using increasing concentrations of alcohol.
Clearing: Replacing alcohol with a substance like xylene that makes the tissue transparent.
Infiltration: Saturating the tissue with a medium like paraffin wax that will support the tissue structure when solidified.
What is Embedding?
Embedding involves placing the processed tissue into a solid medium, usually
paraffin wax, to provide support during sectioning. The tissue is oriented in a mold, and molten wax is poured over it to form a solid block.
How to Section the Tissue?
Sectioning is the process of cutting thin tissue slices using a
microtome. The sections are typically 4-5 micrometers thick. Proper technique is essential to avoid artifacts and ensure that the sections are uniform and intact.
How to Mount and Examine Tissue Sections?
After staining, tissue sections are mounted on glass slides using a mounting medium and a coverslip. The slides are then examined under a
microscope. Proper mounting ensures that the sections are preserved and can be examined repeatedly without degradation.
What are Common Artifacts and How to Avoid Them?
Artifacts are distortions or alterations in tissue sections that can mislead interpretation. Common artifacts include folding, tearing, and bubbles. These can be minimized by following proper techniques during fixation, processing, sectioning, and staining.
Conclusion
Proper technique in histology is essential for obtaining accurate and reliable results. Each step, from tissue preparation to examination, must be performed meticulously. By understanding and applying these techniques, histologists can effectively study tissue structure and contribute valuable insights to medical science.
