A wet mount is a fundamental technique for preparing microscope slides, allowing for the observation of specimens suspended in a liquid medium. This method involves placing a sample in a drop of liquid between a microscope slide and a coverslip. It is widely used in biology and educational settings to examine living organisms or those best viewed in their natural, hydrated state.
Why Use a Wet Mount?
Preparing a wet mount offers advantages for observing living organisms and their movements. This technique allows observation in their natural liquid environment, maintaining hydration and preserving their characteristics. Common applications include viewing microorganisms from pond water, observing human cheek cells, or examining thin sections of plant tissues like onion skin. The wet mount technique helps in assessing motility and behavior, offering a dynamic view that other slide preparation methods might not provide.
Gathering Your Materials
To prepare a wet mount, several basic materials are necessary. You will need clean glass microscope slides. Thin, flat coverslips are placed over the specimen and liquid, protecting the sample and flattening it for observation. A dropper or pipette is used to precisely transfer the liquid medium, such as distilled water or a saline solution, to the slide. Finally, the specimen itself, such as pond water or a small piece of tissue, is needed.
Step-by-Step Preparation
Place a clean microscope slide on a flat surface. Using a dropper or pipette, place a small drop of the liquid medium, such as water or saline, in the center of the slide. The drop should be appropriately sized for your coverslip. Next, carefully transfer your specimen into this liquid drop; if it’s a solid sample, use tweezers to place it, ensuring it is fully immersed.
To prevent air bubbles, hold a coverslip at a 45-degree angle with one edge touching the liquid next to the specimen. Slowly and gently lower the coverslip over the drop, allowing the liquid to spread evenly as it settles. This angled approach helps push out any trapped air. If excess liquid seeps from under the coverslip, gently blot it away with the edge of a paper towel, being careful not to disturb the coverslip.
Tips for Optimal Viewing
Proper microscope use enhances observation. Start viewing your slide under the lowest magnification objective lens to locate the specimen. Adjust the coarse focus knob first, then fine-tune with the fine adjustment knob for clarity. If air bubbles are present, they typically appear as dark, circular outlines and can usually be distinguished from your specimen.
Adjusting the microscope’s light source, such as the diaphragm, can improve contrast and visibility. If the specimen appears to move rapidly or drift out of focus, it might indicate too much liquid on the slide. Conversely, if the liquid dries out too quickly, you may need to add a small drop of water to the edge of the coverslip, allowing it to be drawn underneath.
Safety Considerations
Safety practices are important to prevent injuries and contamination. Always handle glass microscope slides and coverslips carefully to avoid cuts, as their edges can be sharp. Dispose of broken glass in designated sharps containers, not in general waste bins.
Ensure your workspace is clean before and after preparation. If working with biological samples, follow proper disposal guidelines for biological waste, which may include sterilization or specific waste bins. Additionally, wash your hands thoroughly after handling specimens and materials to prevent any potential contamination.