There are cells that when viewed under a microscope look transparent, in many cases, the use of staining techniques to increase the contrast of the details you want to see, however, dyes usually kill the cell, so they are useful mostly with dead cells. When viewing living cell structures, a phase-contrast microscope is best.
Phase contrast microscopes are equipment used for the observation of living cells. In these devices, light is manipulated, so that there is a phase difference between the light waves passing through the sample, thus generating a contrast in the cell that allows a better view of structures that are transparent and impossible to see in a conventional microscope.
History of phase contrast microscope
The phase contrast microscope was created by the physicist Frits Zernike in 1932, his invention came as a consequence of the impossibility of observing certain structures in the cells, since to do so they needed to resort to the use of stains, however, the use of the same led to the death of the cell and what was desired was to visualize them alive.
This team, which awarded the inventor the Nobel Prize in Physics in 1953, is based on the manipulation of the light that reaches the samples and the different refractive indices of the structures that make up the cells in the study sample, in order to increase the contrast of the same, this allows them to be visible and can be studied. This is why they are the best option when you want to see living cells to detail some cellular process.
Basics of phase contrast microscopes
The phase contrast microscope, in structure, is very similar to a conventional light-field microscope, however, it has certain modifications in the lenses and capacitor. Starting with the capacitor, it has a disk that projects the light in an annular way. On the other hand, phase rings are placed on the lenses, which are nothing more than disks with relief, can be positive or negative, depending on the choice, the images that are seen through the eyepiece will be different.
Its foundation is based on the refractive indices of the structures of the cells, when light passes through these structures, it experiences delays or lags, which, thanks to the help of adaptations of the capacitor and lenses, translate into an increase in contrast of these areas, so that they can be easily observed.
Applications of phase contrast microscopes
The phase contrast microscope, due to its characteristics of increasing the contrast of the structures, which for a conventional light-field microscope would be impossible to see without the use of stains, allows it to be a very useful tool when you want to do in vivo examinations in which the cell should not be killed.
So, the phase contrast microscope can be used to look at large numbers of living microorganisms, living cells, and tissues. The invention of this equipment allowed a great advance in biology, since it was possible to observe a great variety of processes, which to date, had been impossible, because in the light-field microscope only samples that are already dead can be observed.
Advantages and disadvantages of phase contrast microscopes
With regard to clear-field microscopes, with these you do not need to color the tissues or cells to observe to increase the contrast of the structures, so that the cells are not required to be dead and also, the same are not damaged, product of staining. Whenever a sample is required to be viewed without damaging it, the technology of these microscopes is most useful.
However, it has certain disadvantages, for example, cells are surrounded by an aura, in the case of negative phase contrast microscopes, this aura is more like a shadow, on the other hand, in the case of positive contrast, it is a bright beam of light. However, although it can become annoying, the advantage of its use is much greater.
Kalstein branded microscopes
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