Darkfield microscopy

Definition

Darkfield microscopy is a technique that enhances contrast in unstained samples by illuminating them with light that will not be collected by the objective lens. This results in a bright image on a dark background, making it useful for observing live and delicate specimens.

5 Must Know Facts For Your Next Test

1. Darkfield microscopy is especially useful for detecting spirochetes, such as those causing Lyme disease and syphilis.
2. It allows visualization of live bacteria in blood or lymphatic fluid without staining, which can be crucial for diagnosing infections.
3. The technique relies on scattered light to produce high-contrast images of small structures like bacterial cells.
4. Specialized darkfield condensers are required to block the central light and only allow peripheral light to illuminate the sample.
5. Darkfield microscopy can help identify fast-moving microorganisms that might be missed using other techniques.

Review Questions

• How does darkfield microscopy enhance the visibility of unstained samples?
• Why is darkfield microscopy particularly useful for detecting spirochetes in blood or lymphatic fluid?
• What kind of equipment modification is necessary to perform darkfield microscopy?

Related terms

Phase Contrast Microscopy: A technique that converts phase shifts in light passing through a transparent specimen to brightness changes in the image.

Fluorescence Microscopy:

Uses high-intensity illumination to excite fluorophores in the sample, producing a bright emission against a dark background.

Spirochetes: A group of motile bacteria with spiral shapes, often associated with diseases like Lyme disease and syphilis.