Fluorescence Microscopy

Certain compounds when exposed to short wavelength radiations, e.g., UV and X-rays. absorb and emit energy as light of a longer wavelength. This process of emitting light from a compound is known as fluorescence and is now commonly used in microscopy. Compounds which naturally emit light exist in most living tissues. For example, the mitochondria of liver and kidney, collagen and chlorophyll give a strong fluorescence. Such a type of natural fluorescence is called as autofluorescence. Sometimes fluorescent dyes llKe rhodamine, quinacrine etc. called fluorochromes are used to stain cell components to produce secondary fluorescence. Such important dyes are also used in the study of chromosome behaviour.

The fluorescent microscope is essentially an ordinary optical instrument. It has been modified by the incorporation of special filters. These filters allow only the required wavelength of light to pass and cause fluorescence in the specimen. The most significant application of fluorescent microscopy is in the field of immuno-fluorescent,antibody labelling technique about which you will study later in this Unit.