Light microscopy sample preparation

The long history of light microscopy and its wide application have resulted in countless sample preparation techniques. Some specimens can be simply mounted on a microscopy slide.

Often additional steps are required to achieve satisfying results. Most of these methods kill the cells, hence light microscopy is not ideal to visualize processes in living cells. Protocols vary depending on the sample and microscope. Below is the general process for histology preparations.

Preparation:

• Fixation - chemical fixatives preserve tissue by preventing degradation, and help to maintain the structure of the cell and of sub-cellular components. The most common fixative for light microscopy is 10% neutral buffered formalin.

• Dehydration - water is removed from the sample as it does not mix with embedding media.

• Embedding - the sample is embedded in a solid external matrix to facilitate sectioning.

• Sectioning - the specimen is cut into thin sections. The thickness of the sections depends on the sample and research question. For routine histology, these slices are 2-5 two to five micrometers thick.

• Mounting - attaching samples to the microscopy slide.

• Staining - sample is stained to add contrast and label structures of interest.