A 2.2.2 - Microscopy Skills

preparing a temporary mount

1. Select a thin layer of tissue or cells from a specimen

2. Lay the specimen flat on a clean microscope slide

3. Add a drop of water/stain to keep the cells hydrated or to enhance visibility by highlighting specific shadows

4. lower the cover slip gently at an angle to avoid air bubbles

5. blot away any excess water/stain from the edges using a paper towel.

when are each dyes used

methylene blue to stain animal cells, iodine to stain plant cells

How to focus

1. Start with the lowest magnification

2. Place the slide on the stage, secure with clips, and center the area of interest over light sources

3. Use the coarse focusing knob to bring the specimen into view

4. Use the fine focusing knob when the image is clear to sharpen details

eyepiece graticule

small scale etched onto the eyepiece lens of a microscope that helps you measure in eyepiece units.

how to calibrate an eyepiece graticule using a micrometer

1. place the stage micrometer on the stage of your microscope

2. Start with the lowest power of magnification (4x)

3. Align the stage micrometer with the eyepiece graticule

4. Find the number of divisions of the stage micrometer per eye piece unit

5. divide the total measured units of the graticule by the number of divisions on the eyepiece graticule to find the increment for the smallest division

6. Remove stage micrometer.

Formula magnification

magnification = image size / actual size