What is Phase Contrast and when to use it?

Most of the Biological samples are quite transparent, characteristic that turns difficult its visualization under a Brightfield microscope. To overcome this, scientists frequently treat the samples with different staining solutions in order to enhance their contrast.

Nevertheless, this option cannot be considered when working with living cells, since the chemical toxicity of the staining solutions would kill the cells. This is a particular issue for Microbiologists, who frequently observe living cells (usually in culture), microorganisms, and thin tissue slices.

The Phase Contrast technique, is an easy and smart way to enhance contrast on transparent specimens, and therefore allows the examination of living cells in their natural state.

A phase contrast microscope enhances the change in phase of the light going through the sample and thereby causes a difference in brightness. To see which components you will need to use this technique, and how to set up them on your Motic microscope, please see our Simple Phase Contrast video.

The images below show thin slices of a Rabbit testicle, where the spermatogenesis process can be followed. Both pictures(100X magnified) were taken with a Moticam 5 mounted on the Motic AE2000 inverted microscope. On the left, the sample visualized in Brightfield and on the right with the Phase Contrast technique.