12/31/2022 0 Comments Introduction to light microscopy![]() ![]() ![]() Specialised types of light microscope have been developed to help investigate different aspects of a sample.Ĭonfocal laser scanning fluorescence microscopy(or ‘confocal’ for short) makes it possible to look at different cross-sections of a thick sample without actually cutting the sample up. Other stains are used on living tissue, which is important for observing biological processes under the microscope. Some stains require the sample to be treated beforehand, and in this case, the tissue is no longer living. Stains can be used on living or non-living biological material. In fluorescence microscopy, fluorescent stains are used to highlight specific parts of the cell or tissue. Other common stains include H&E (haematoxylin and eosin), which stains the cell nucleus purple and other tissue components pink. For example, iodine is often used to stain plant cells because it colours the starch stored within the cells a blue colour and other structures a pale brown. Stains interact with a specific part of the sample, turning it a different colour from its surroundings. This is important because these samples often lack contrast, which makes it hard to distinguish between parts of the sample. Preparing biological samplesīiological samples for the light microscope (particularly compound microscopes) often need to be ‘stained’ (coloured) in some way to make it easier for users to understand what they’re seeing. ![]() This makes them very useful for looking at living things, such as flower parts, insects, earthworms and human skin. The advantage of light microscopes (and stereomicroscopes in particular) is that objects can be looked at with little or no preparation. The maximum resolution (and therefore magnification) of light microscopes is quite limited compared to electron microscopes – at best, they can magnify up to approximately 2000 times. Specialised microscopes can provide different kinds of information about a microscope sample so that scientists can choose the microscope that is most likely to answer their questions about their sample. Over time, specialised light microscopes have been developed such as the confocal laser scanning fluorescence microscope and the polarised light microscope. Some want to look at a surface of an object, while others want to see its inner workings some want to see processes happening in real time in living things for some, being able to label specific molecules in a sample is important. ![]() Being able to look more closely (that is, at higher magnification and resolution) has always been a major goal, but scientists also have other things on their wish lists. Since Antonie van Leeuwenhoek first saw mysterious ‘animalcules’ (bacteria) through his simple glass lens in the late 1600s, scientists have wanted to understand more about the strange and wonderful things they were discovering by using microscopes. ![]()
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