Staining in Microscopy

Staining is an important part of microscopy that allows you to increase the contrast in certain images so that you can view particular areas of a specimen more clearly. This then allows the viewing of bacteria for instance or other particular specimen and is useful in a lot of research and study. Staining is often used in biology and medicine so that structures can be highlighted in biological tissue. Particular forms of microscopes are often used in order to view these stains.

The easiest way to think about staining and dyes then is as selective highlighter pens that automatically highlight particular areas of a specimen for viewing. This is a slightly more complicated process than that would make it sound however and there are various distinct types of dying and staining in microscopy.

In Vivo or In Vitro?

First of all there is an important distinction to make between in vivo and in vitro staining. In vivo means the 'in life' and essentially then it is the process of dying living tissue. By making certain cells or structures take on highly contrasting hues it is possible to easily seen their form or position in the tissue. In vitro then of course is staining tissues that are no longer alive.

Staining is generally a complicated and scientific process. It is important to find substances that will react with the specific structures and substances that the examiner wishes to view. In some cases a second dye may be used to increase the contrast of a principle dye and make it more visible if it was not immediately.

Staining in microscopy is a technique that is generally associated with light microscopes that use light in order to view the specimen and then scatter this one beam to view it in more detail. However it can also be used with an electron microscope in order to increase contrast in the same way and to highlight specific things at an even more microscopic level.

Fluorescence Microscope

This should not be confused with the function of a fluorescence microscope which works in a different way again. A fluorescence microscope is essentially a microscope which uses no light source and instead the object itself is the light source. This is due to the fact that the specimen gives off its own light in the form of fluorescence or phospherescence and that can be used instead of, or as well as reflection or absorption. Here just a small amount of light is used in order to trigger the fluorescence in the sample so that it creates its own light. The use of a fluorescence microscope improves the signal to noise ratio.

Interestingly in some cases though this fluorescence itself will be caused by fluorescent stains in which case staining can go hand in hand with the use of a fluorescent microscope. In other cases though the sample will be intrinsically fluorescent (called autofluorescence) or it will be achieved through the expression of a fluorescent gene – which may be the result of genetic manipulation.

Staining can be very useful when using microscopes. Follow the links for a fluorescence microscope and other equipment.