Light microscopy - Preparing a specimen before investigation

Your specimen (the sample you're looking at) needs to let light through it for you to be able to see it clearly - if you've got quite a thick specimen, you'll need to take a thin slice of it to start with.

Take a clean side (a ***** of clear glass or plastic) and use a pipette to put one drop of water or mountant (a clear, gloopy liquid) in the middle of it - this will secure the specimen in place.

Use tweezers to place your specimen on the slide

Add a drop of stain if needed - if your specimen is completely transparent or colourless, a drop of stain is added to make the specimen easier to see. Different stains are used to highlight different structures or tissues. For example, eosin is used to stain cytoplasm and methylene blue stains DNA.

Place a cover slip (a square thin, transparent plastic or glass) at one end of the specimen, holding it an angle with a mounted needle.

Carefully lower the cover slip onto the slide. Press it down gently with the needle so that no air bubbles are trapped under it.