Staining

The cornerstone of fluorescence microscopy is the principle of fluorescent emission. Molecules exposed to a certain wavelength will emit a longer wavelength (different color). The stains contain microscopic fluorochromes that target certain molecules in the tissue, a process called biological labelling. When the stains are exposed to a certain light, they absorb and emit a wavelength back that can be viewed by a fluorescence microscope.

BS lectin and Zn12 are commonly used in the biology labs at Depauw University. BS lectin is a poisonous, carbohydrate-binding molecule found in plants. It has the useful ability to bind to carbohydrates on the surface of endothelial cells. Blood vessels are lined with endothelial cells, enabling the identification and labeling of these structures with BS lectin.

Zn12 stains for neurons. Zn12 requires the use of a primary antibody and a secondary antibody. The primary antibody binds to the host's target antigen, specifically the epitope, but it isn't naturally fluorescent. Thus, it needs another molecule to bind to it to enable visualization of the target structure. This is the role of the secondary antibody. Finally, after the sample is incubated in the secondary antibody, the sample can be loaded onto the Zeiss microscope for imaging.