What is Mounting?
Mounting is a crucial step in the preparation of histological slides. It involves placing the tissue section on a glass slide and covering it with a thin layer of medium and a coverslip. This process is essential for preserving the tissue and enhancing the visibility of cellular details under a microscope.
Why is Mounting Important?
Mounting is critical for several reasons. Firstly, it protects the tissue from physical damage and contamination. Secondly, it ensures that the tissue remains flat and in place during microscopic examination. Thirdly, the mounting medium can improve the optical properties of the sample, making cellular structures more visible and easier to analyze.
Types of Mounting Media
There are various types of
mounting media used in histology, each with its own advantages and applications:
Aqueous Media: These are water-based and are often used for temporary mounts or for specimens that are sensitive to organic solvents.
Permanent Media: These are solvent-based and are used for long-term preservation of tissue sections. Examples include Canada balsam and synthetic resins like DPX.
Fluorescent Media: These are specialized media that protect fluorescent dyes from photobleaching, ensuring that the fluorescence signal remains stable over time.
Steps in the Mounting Process
The mounting process involves several meticulous steps to ensure the quality and integrity of the tissue sample: Sectioning: Thin sections of tissue are cut using a microtome and placed on a glass slide.
Staining: The sections are stained to highlight specific cellular structures. Common stains include hematoxylin and eosin (H&E).
Dehydration: If a non-aqueous mounting medium is to be used, the tissue is dehydrated through a series of alcohol solutions.
Clearing: The tissue is then cleared using a solvent like xylene to make it transparent.
Mounting: A drop of mounting medium is placed on the tissue, and a coverslip is carefully applied to avoid air bubbles.
Common Issues and Troubleshooting
Despite careful preparation, several issues can arise during the mounting process: Air Bubbles: These can obscure the view of the tissue. They can be minimized by applying the coverslip slowly and evenly.
Tissue Wrinkling: This can occur if the tissue is not properly flattened before mounting. Ensuring the sections are adequately flattened during sectioning can prevent this.
Mounting Medium Artifacts: Imperfections in the mounting medium can create artifacts. Using high-quality, filtered mounting media can reduce these issues.
Conclusion
Mounting is a vital step in the preparation of histological slides. It involves the careful application of a mounting medium and coverslip to protect the tissue and enhance its visibility under a microscope. Understanding the types of mounting media and the steps involved in the mounting process is essential for producing high-quality histological slides, crucial for accurate diagnosis and research.
