Cytology methods

A variety of methods are used to study the functioning of cells.

Light microscopy

• In 1590 the first microscope was created (by the Jansen brothers).
• At the beginning of the 17th century, the first microscopes were created in which image magnification was created using a lens system.
• In 1665, the English physicist and botanist Robert Hooke used a microscope to study living organisms (he examined an elderberry branch) and saw cells (in fact, these were cell walls, but Hooke introduced the name “cell”).
• In 1696, Anthony van Leeuwenhoek described erythrocytes, spermatozoa, microorganisms in his book “Secrets of Nature Discovered with the Most Perfect Microscopes” (therefore van Leeuwenhoek is considered the founder of biological microscopy).

The light microscope was the main “weapon” of biologists in the 18th – 19th centuries. Now it is also used, but in such a microscope it is not possible to see structures if they are less than the wavelength of light.

In the early 30s of the XX century, an electron microscope appeared, which made it possible to examine the components of cells with a size of only 1 nm. This device makes it possible to obtain images of objects through the use of an electron beam.

Modern methods of fluorescence and confocal microscopy allow obtaining microscopic images with maximum resolution.

The scanning electron microscope makes it possible to obtain three-dimensional images of objects.

A significant drawback of an electron microscope is the impossibility of examining living cells (before examination with an electron microscope, cells must be subjected to special processing, as a result of which they die). Therefore, if it is necessary to observe long-term processes occurring in a living cell, slow motion filming is used through powerful light microscopes.

If you want to follow the fate of a chemical compound in a cell, you can replace one of the atoms in its molecule with a radioactive isotope (the isotopes of phosphorus (32P), hydrogen (3H) and carbon (14C) are most often used). Then this molecule will have a radioactive label, by which it can be detected using special devices or by its ability to light up photographic film.

To isolate and study individual cell organelles, the method of ultracentrifugation is used: tubes with cellular material are very quickly rotated in special devices – centrifuges. Cell organelles differ in their masses and sizes, therefore, under the action of centrifugal force, they settle at different speeds. This is how mitochondria, ribosomes and some other organelles of the cell are secreted.

Now scientists can also use various modern methods to study the cell at the molecular level, in connection with which the science of molecular biology is actively developing.