The importance of the microscope in the modern world. A Brief History of the Development of Biology - Knowledge Hypermarket

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Microscopy technology has opened up new possibilities in medical and laboratory practice. Today, neither diagnostic studies nor surgical interventions can do without special optics. The most significant role of microscopes in dentistry, ophthalmology, microsurgery. This is not just about improving visibility and facilitating work, but about a fundamentally new approach to research and operations.

The impact on fine structures at the cellular level means that the patient will more easily endure the intervention, recover faster, and will not suffer damage to healthy tissues and complications. Behind all these advantages of modern medicine is often a microscope - a powerful high-tech device, designed using the latest advances in optics.

Depending on the purpose, microscopes are divided into:

• laboratory;
• dental;
• surgical;
• ophthalmic;
• otolaryngological.

Optical systems for biochemical, hematological, dermatological, cytological studies are functionally different from medical ones. Ophthalmic microscopes are recognized as the most advanced and powerful - with their help, it was possible to make a radical breakthrough in the treatment of cataracts, hyperopia, myopia, astigmatism. Operations at the micron level, performed under 40x magnification, are comparable in invasiveness to an injection, the patient recovers after surgery in a matter of days.

No less interesting are those that allow, under 25x magnification, to accurately treat dental canals and other smallest structures that are not visible to the human eye. Using the latest optics, dentists almost always manage to provide high-quality treatment and save the tooth.

Magnifying devices for microsurgery are characterized by an extended field of view, increased image sharpness, and the possibility of smooth or stepwise adjustment of the magnification. All this provides the best visibility conditions for the surgeon and assistants.

It is important that the new generation of instruments for microscopy is as convenient as possible to use: working with magnifying optics is simple and does not require much effort or special skills. Due to the built-in lighting system and the convenient shape of the eyepiece, the specialist does not experience fatigue and discomfort even during long continuous work.

A microscope is a fragile instrument that needs to be handled with care. This is especially true of lenses: it is undesirable to touch the optical surfaces with your hands; a special brush and soft wipes soaked in ethyl alcohol are used to clean the device.

Rooms containing microscopes should be maintained at room temperature and low humidity (less than 60%).

Today it is difficult to imagine the scientific activity of man without a microscope. The microscope is widely used in most laboratories of medicine and biology, geology and materials science.

The results obtained using a microscope are necessary for making an accurate diagnosis and monitoring the course of treatment. With the use of a microscope, new drugs are developed and introduced, scientific discoveries are made.

Microscope- (from the Greek mikros - small and skopeo - I look), an optical device for obtaining an enlarged image of small objects and their details that are not visible to the naked eye.

The human eye is able to distinguish the details of an object that are at least 0.08 mm apart from each other. Using a light microscope, you can see the details, the distance between which is up to 0.2 microns. An electron microscope allows you to get a resolution of up to 0.1-0.01 nm.

The invention of the microscope, an instrument so important for all science, is primarily due to the influence of the development of optics. Some optical properties of curved surfaces were known even to Euclid (300 BC) and Ptolemy (127-151), but their magnifying power did not find practical application. In this regard, the first glasses were invented by Salvinio deli Arleati in Italy only in 1285. In the 16th century, Leonardo da Vinci and Maurolico showed that small objects are best studied with a magnifying glass.

The first microscope was created only in 1595 by Z. Jansen. The invention consisted in the fact that Zacharius Jansen mounted two convex lenses inside one tube, thereby laying the foundation for the creation of complex microscopes. Focusing on the object under study was achieved by a retractable tube. The magnification of the microscope was from 3 to 10 times. And it was a real breakthrough in the field of microscopy! Each of his next microscope, he significantly improved.

During this period (XVI century) Danish, English and Italian research instruments gradually began to develop, laying the foundation for modern microscopy.

The rapid spread and improvement of microscopes began after Galileo (G. Galilei), improving the telescope he designed, began to use it as a kind of microscope (1609-1610), changing the distance between the objective and the eyepiece.

Later, in 1624, having achieved the production of shorter focus lenses, Galileo significantly reduced the dimensions of his microscope.

In 1625, a member of the Roman Academy of the Vigilant ("Akudemia dei lincei") I. Faber proposed the term "microscope". The first successes associated with the use of a microscope in scientific biological research were achieved by R. Hooke, who was the first to describe a plant cell (about 1665). In his book "Micrographia" Hooke described the structure of the microscope.

In 1681, the Royal Society of London in their meeting discussed in detail the peculiar situation. Dutchman Leeuwenhoek(A. van Leenwenhoek) described the amazing miracles that he discovered with his microscope in a drop of water, in an infusion of pepper, in the mud of a river, in the hollow of his own tooth. Leeuwenhoek, using a microscope, discovered and sketched the spermatozoa of various protozoa, details of the structure of bone tissue (1673-1677).

"With the greatest amazement, I saw in the drop a great many little animals moving briskly in all directions, like a pike in water. The smallest of these tiny animals is a thousand times smaller than the eye of an adult louse."

The best Leeuwenhoek magnifiers were magnified 270 times. With them, he saw for the first time the blood corpuscles, the movement of blood in the capillary vessels of the tadpole's tail, the striation of the muscles. He opened infusoria. For the first time he plunged into the world of microscopic unicellular algae, where the border between animal and plant lies; where a moving animal, like a green plant, has chlorophyll and feeds by absorbing light; where the plant, still attached to the substrate, has lost chlorophyll and is ingesting bacteria. Finally, he even saw bacteria in great variety. But, of course, at that time there was still no remote possibility of understanding either the significance of bacteria for humans, or the meaning of the green substance - chlorophyll, or the boundary between plant and animal.

A new world of living beings was opening up, more diverse and infinitely more original than the world we see.

In 1668, E. Divini, having attached a field lens to the eyepiece, created an eyepiece of the modern type. In 1673, Haveliy introduced a micrometer screw, and Hertel suggested placing a mirror under the microscope stage. Thus, the microscope began to be assembled from those main parts that are part of a modern biological microscope.

In the middle of the 17th century newton discovered the complex composition of white light and decomposed it with a prism. Römer proved that light travels at a finite speed and measured it. Newton put forward the famous hypothesis - incorrect, as you know - that light is a stream of flying particles of such extraordinary fineness and frequency that they penetrate through transparent bodies, like glass through the lens of the eye, and, hitting the retina with impacts, produce a physiological sensation of light . Huygens was the first to speak of the undulating nature of light and proved how naturally it explains both the laws of simple reflection and refraction, and the laws of double refraction in Icelandic spar. The thoughts of Huygens and Newton met in sharp contrast. Thus, in the XVII century. in a sharp dispute, the problem of the essence of light really arose.

Both the solution to the question of the essence of light and the improvement of the microscope moved forward slowly. The dispute between the ideas of Newton and Huygens continued for a century. The famous Euler joined the idea of ​​the wave nature of light. But the issue was resolved only after more than a hundred years by Fresnel, a talented researcher, such as science knew.

What is the difference between the flow of propagating waves - the idea of ​​Huygens - from the flow of rushing small particles - the idea of ​​Newton? Two signs:

1. Having met, the waves can mutually annihilate if the hump of one lies on the valley of the other. Light + light combined together can produce darkness. This phenomenon interference, these are Newton's rings, misunderstood by Newton himself; this cannot be the case with particle flows. Two streams of particles are always a double stream, a double light.

2. The flow of particles passes through the hole directly, without diverging to the sides, and the flow of waves certainly diverges, dissipates. This diffraction.

Fresnel proved theoretically that the divergence in all directions is negligible if the wave is small, but nevertheless he discovered and measured this negligible diffraction, and determined the wavelength of light from its magnitude. Of the interference phenomena that are so well known to opticians who polish to "one color", to "two bands", he also measured the wavelength - this is half a micron (half a thousandth of a millimeter). And hence the wave theory and the exceptional subtlety and sharpness of penetration into the essence of living matter became undeniable. Since then, we all confirm and apply Fresnel's ideas in various modifications. But even without knowing these thoughts, one can improve the microscope.

So it was in the 18th century, although events developed very slowly. Now it is difficult even to imagine that Galileo's first tube, through which he observed the world of Jupiter, and Leeuwenhoek's microscope were simple non-achromatic lenses.

A huge obstacle to achromatization was the lack of a good flint. As you know, achromatization requires two glasses: crown and flint. The latter is glass, in which one of the main parts is heavy lead oxide, which has a disproportionately large dispersion.

In 1824, Sallig's simple practical idea, reproduced by the French firm of Chevalier, gave a tremendous success to the microscope. The lens, which used to consist of a single lens, is divided into parts, it began to be made from many achromatic lenses. Thus, the number of parameters was multiplied, the possibility of correcting system errors was given, and for the first time it became possible to talk about real large magnifications - by 500 and even 1000 times. The boundary of ultimate vision has moved from two to one micron. Leeuwenhoek's microscope is left far behind.

In the 70s of the 19th century, the victorious march of microscopy moved forward. The one who said was Abbe(E. Abbe).

The following has been achieved:

First, the limiting resolution has moved from half a micron to one tenth of a micron.

Secondly, in the construction of the microscope, instead of rough empiricism, a high scientific character has been introduced.

Thirdly, finally, the limits of the possible with a microscope are shown, and these limits are conquered.

A headquarters of scientists, opticians and calculators working at the Zeiss firm was formed. Abbe's pupils presented the theory of the microscope and of optical instruments in general in major works. A system of measurements has been developed that determines the quality of a microscope.

When it turned out that the existing types of glass could not meet scientific requirements, new types were systematically created. Outside the secrets of the heirs of Guinan - Para-Mantua (the heirs of Bontan) in Paris and the Chances in Birmingham - glass melting methods were again created, and the matter of practical optics was developed to such an extent that one can say: Abbe almost won the world war of 1914-1918 with optical equipment of the army gg.

Finally, calling to the aid of the foundations of the wave theory of light, Abbe clearly showed for the first time that each sharpness of the instrument has its own limit of possibility. The thinnest of all instruments is the wavelength. It is impossible to see objects smaller than half the wavelength, says Abbe's diffraction theory, and it is impossible to obtain images smaller than half the wavelength, i.e. less than 1/4 micron. Or with various tricks of immersion, when we use media in which the wavelength is shorter - up to 0.1 micron. The wave limits us. True, the limits are very small, but still these are limits for human activity.

An optical physicist feels when an object a thousandth, ten thousandth, in some cases even one hundred thousandth of a wavelength is inserted in the path of a light wave. The wavelength itself is measured by physicists with an accuracy of one ten-millionth of its magnitude. Is it possible to think that opticians, who have joined their efforts with cytologists, will not master the hundredth wavelength that stands in their task? There are dozens of ways to get around the wavelength limit. You know one of these bypasses, the so-called ultramicroscopy method. If the microbes invisible in the microscope are far apart, then you can illuminate them from the side with a bright light. No matter how small they are, they will shine like a star against a dark background. Their form cannot be determined, one can only ascertain their presence, but this is often extremely important. This method is widely used in bacteriology.

The works of the English optician J. Sirks (1893) laid the foundation for interference microscopy. In 1903 R. Zsigmondy and N. Siedentopf created an ultramicroscope, in 1911 M. Sagnac described the first two-beam interference microscope, in 1935 F. Zernicke proposed use the phase contrast method to observe transparent, weakly light-scattering objects in microscopes. In the middle of the XX century. the electron microscope was invented, in 1953 the Finnish physiologist A. Wilska invented the anoptral microscope.

M.V. Lomonosov, I.P. Kulibin, L.I. Mandelstam, D.S. Rozhdestvensky, A.A. Lebedev, S.I. Vavilov, V.P. Linnik, D.D. Maksutov and others.

Literature:

D.S. Rozhdestvensky Selected Works. M.-L., "Science", 1964.

Rozhdestvensky D.S. On the question of the image of transparent objects in a microscope. - Tr. GOI, 1940, v. 14

Sobol S.L. History of the microscope and microscopic research in Russia in the 18th century. 1949.

Clay R.S., Court T.H. The history of the microscope. L., 1932; Bradbury S. The evolution of the microscope. Oxford, 1967.

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Abstract on the topic:

Modern methods of microscopic research

Completed by a student

2nd year 12 groups

Schukina Serafima Sergeevna

Introduction

1. Types of microscopy

1.1 Light microscopy

1.2 Phase contrast microscopy

1.3 Interference microscopy

1.4 Polarizing microscopy

1.5 Fluorescence microscopy

1.6 Ultraviolet microscopy

1.7 Infrared microscopy

1.8 Stereoscopic microscopy

1.9 Electron microscopy

2. Some types of modern microscopes

2.1 Historical background

2.2 The main components of the microscope

2.3 Microscope types

Conclusion

List of used literature

Introduction

Microscopic research methods - ways to study various objects using a microscope. In biology and medicine, these methods make it possible to study the structure of microscopic objects whose dimensions lie beyond the resolution of the human eye. The basis of microscopic research methods (M.m.i.) is light and electron microscopy. In practical and scientific activities, doctors of various specialties - virologists, microbiologists, cytologists, morphologists, hematologists, etc., in addition to conventional light microscopy, use phase-contrast, interference, luminescent, polarization, stereoscopic, ultraviolet, infrared microscopy. These methods are based on various properties of light. In electron microscopy, the image of the objects of study arises due to the directed flow of electrons.

microscopy polarizing ultraviolet

1. Types of microscopy

1.1 Light microscopy

For light microscopy and other M.m.i. In addition to the resolution of the microscope, the determining factor is the nature and direction of the light beam, as well as the features of the object under study, which can be transparent and opaque. Depending on the properties of the object, the physical properties of light change - its color and brightness associated with the wavelength and amplitude, phase, plane and direction of wave propagation. On the use of these properties of light, various M. m. and are built. For light microscopy, biological objects are usually stained in order to reveal one or another of their properties ( rice. one ). In this case, the tissues must be fixed, since staining reveals certain structures of only killed cells. In a living cell, the dye is isolated in the cytoplasm in the form of a vacuole and does not stain its structure. However, living biological objects can also be studied in a light microscope using the method of vital microscopy. In this case, a dark-field condenser is used, which is built into the microscope.

Rice. Fig. 1. Myocardial micropreparation in case of sudden death from acute coronary insufficiency: Lee staining reveals contracture overcontractions of myofibrils (areas of red color); Ch250.

1.2 Phase contrast microscopy

Phase-contrast microscopy is also used to study living and unstained biological objects. It is based on the diffraction of a beam of light depending on the characteristics of the radiation object. This changes the length and phase of the light wave. The objective of a special phase-contrast microscope contains a translucent phase plate. Living microscopic objects or fixed, but not colored, microorganisms and cells, due to their transparency, practically do not change the amplitude and color of the light beam passing through them, causing only a phase shift of its wave. However, after passing through the object under study, the light rays deviate from the translucent phase plate. As a result, a difference in wavelength arises between the rays that have passed through the object and the rays of the light background. If this difference is at least 1/4 of the wavelength, then a visual effect appears, in which a dark object is clearly visible against a light background, or vice versa, depending on the features of the phase plate.

1.3 interference microscopy

Interference microscopy solves the same problems as phase-contrast microscopy. But if the latter allows us to observe only the contours of the objects of study, then with the help of interference microscopy it is possible to study the details of a transparent object and carry out their quantitative analysis. This is achieved by bifurcating a beam of light in a microscope: one of the beams passes through the particle of the observed object, and the other passes by it. In the eyepiece of a microscope, both beams are connected and interfere with each other. The resulting phase difference can be measured by determining thus. many different cellular structures. Sequential measurement of the phase difference of light with known refractive indices makes it possible to determine the thickness of living objects and non-fixed tissues, the concentration of water and dry matter in them, the content of proteins, etc. Based on interference microscopy data, one can indirectly judge the permeability of membranes, enzyme activity, cellular metabolism of the objects of study.

1.4 Polarizing microscopy

Polarizing microscopy makes it possible to study objects of study in light formed by two beams polarized in mutually perpendicular planes, i.e., in polarized light. To do this, filmy polaroids or Nicol prisms are used, which are placed in a microscope between the light source and the preparation. Polarization changes during the passage (or reflection) of light rays through various structural components of cells and tissues, the properties of which are inhomogeneous. In the so-called isotropic structures, the propagation velocity of polarized light does not depend on the plane of polarization; in anisotropic structures, its propagation velocity varies depending on the direction of the light along the longitudinal or bath light in the norm.

Rice. 2a). Micropreparation of the myocardium in the polarization of the transverse axis of the object.

If the refractive index of light along the structure is greater than in the transverse direction, positive birefringence occurs, with reverse relationships - negative birefringence. Many biological objects have a strict molecular orientation, are anisotropic and have positive double refraction of light. Myofibrils, cilia of the ciliated epithelium, neurofibrils, collagen fibers, etc. have such properties. fig.2 ). Polarizing microscopy is one of the histological research methods, a method of microbiological diagnostics, is used in cytological studies, etc. At the same time, both stained and unstained and non-fixed, so-called native preparations of tissue sections, can be examined in polarized light.

Rice. 2b). A micropreparation of the myocardium in polarized light with sudden death from acute coronary insufficiency - areas are identified in which there is no characteristic transverse striation of cardiomyocytes; Ch400.

1.5 Fluorescent microscopy

Fluorescent microscopy is widely used. It is based on the property of some substances to give luminescence - luminescence in UV rays or in the blue-violet part of the spectrum. Many biological substances, such as simple proteins, coenzymes, some vitamins and drugs, have their own (primary) luminescence. Other substances begin to glow only when special dyes are added to them - fluorochromes (secondary luminescence). Fluorochromes can be diffusely distributed in a cell or selectively stain individual cell structures or certain chemical compounds of a biological object. This is the basis for the use of luminescent microscopy in cytological and histochemical studies. With the help of immunofluorescence in a fluorescent microscope, viral antigens and their concentration in cells are detected, viruses are identified, antigens and antibodies, hormones, various metabolic products, etc. are determined. ( rice. 3 ). In this regard, luminescent microscopy is used in the laboratory diagnosis of infections such as herpes, mumps, viral hepatitis, influenza, etc., is used in the rapid diagnosis of respiratory viral infections, examining prints from the nasal mucosa of patients, and in the differential diagnosis of various infections. In pathomorphology, using luminescent microscopy, malignant tumors are recognized in histological and cytological preparations, areas of ischemia of the heart muscle are determined in the early stages of myocardial infarction, and amyloid is detected in tissue biopsies.

Rice. 3. Micropreparation of peritoneal macrophage in cell culture, fluorescent microscopy.

1.6 ultraviolet microscopy

Ultraviolet microscopy is based on the ability of certain substances that make up living cells, microorganisms, or fixed, but not stained, transparent tissues in visible light, to absorb UV radiation with a certain wavelength (400-250 nm). High-molecular compounds, such as nucleic acids, proteins, aromatic acids (tyrosine, tryptophan, methylalanine), purine and pyramidine bases, etc., have this property. Using ultraviolet microscopy, the localization and amount of these substances are specified, and in the case of studying living objects, their changes in the process of life.

1.7 infrared microscopy

Infrared microscopy makes it possible to study objects that are opaque to visible light and UV radiation by absorbing light with a wavelength of 750–1200 nm by their structures. Infrared microscopy does not require prior chem. drug processing. This type of M. m. and. most often used in zoology, anthropology, and other branches of biology. In medicine, infrared microscopy is mainly used in neuromorphology and ophthalmology.

1.8 stereoscopic microscopy

Stereoscopic microscopy is used to study volumetric objects. The design of stereoscopic microscopes allows you to see the object of study with the right and left eyes from different angles. Explore opaque objects at relatively low magnification (up to 120x). Stereoscopic microscopy finds application in microsurgery, in pathomorphology with a special study of biopsy, surgical and sectional material, in forensic laboratory research.

1.9 electron microscopy

Electron microscopy is used to study the structure of cells, tissues of microorganisms and viruses at the subcellular and macromolecular levels. This M. m. and. allowed to move to a qualitatively new level of study of matter. It has found wide application in morphology, microbiology, virology, biochemistry, oncology, genetics, and immunology. A sharp increase in the resolution of an electron microscope is provided by the flow of electrons passing in vacuum through electromagnetic fields created by electromagnetic lenses. Electrons can pass through the structures of the object under study (transmission electron microscopy) or be reflected from them (scanning electron microscopy), deviating at different angles, resulting in an image on the luminescent screen of the microscope. With transmission (transmission) electron microscopy, a planar image of structures is obtained ( rice. 4 ), with scanning - volumetric ( rice. 5 ). The combination of electron microscopy with other methods, for example, autoradiography, histochemical, immunological research methods, allows for electron radioautographic, electron histochemical, electron immunological studies.

Rice. 4. Electron diffraction pattern of a cardiomyocyte obtained by transmission (transmission) electron microscopy: subcellular structures are clearly visible; Ch22000.

Electron microscopy requires special preparation of objects of study, in particular chemical or physical fixation of tissues and microorganisms. Biopsy material and sectional material after fixation are dehydrated, poured into epoxy resins, cut with glass or diamond knives on special ultratomes, which make it possible to obtain ultrathin tissue sections with a thickness of 30–50 nm. They are contrasted and then examined under an electron microscope. In a scanning (raster) electron microscope, the surface of various objects is studied by depositing electron-dense substances on them in a vacuum chamber, and examining the so-called. replicas that follow the contours of the sample.

Rice. 5. Electron diffraction pattern of a leukocyte and a bacterium phagocytosed by it obtained by scanning electron microscopy; CH20000.

2. Some types of modern microscopes

Phase contrast microscope(anoptral microscope) is used to study transparent objects that are not visible in a bright field and are not subject to staining due to the occurrence of anomalies in the samples under study.

interference microscope makes it possible to study objects with low refractive indices and extremely small thicknesses.

Ultraviolet and infrared microscopes designed to study objects in the ultraviolet or infrared part of the light spectrum. They are equipped with a fluorescent screen on which an image of the test preparation is formed, a camera with photographic material sensitive to these radiations, or an electron-optical converter for forming an image on the oscilloscope screen. The wavelength of the ultraviolet part of the spectrum is 400-250 nm, therefore, a higher resolution can be obtained in an ultraviolet microscope than in a light microscope, where illumination is carried out by visible light radiation with a wavelength of 700-400 nm. The advantage of this M. is also that objects invisible in a conventional light microscope become visible, since they absorb UV radiation. In an infrared microscope, objects are observed on the screen of an electron-optical converter or photographed. Infrared microscopy is used to study the internal structure of opaque objects.

polarizing microscope allows you to identify heterogeneities (anisotropy) of the structure when studying the structure of tissues and formations in the body in polarized light. Illumination of the preparation in a polarizing microscope is carried out through a polarizer-plate, which ensures the passage of light in a certain plane of wave propagation. When polarized light, interacting with structures, changes, the structures contrast sharply, which is widely used in biomedical research when studying blood products, histological preparations, sections of teeth, bones, etc.

Fluorescent microscope(ML-2, ML-3) is designed to study luminescent objects, which is achieved by illuminating the latter with UV radiation. By observing or photographing preparations in the light of their visible excited fluorescence (i.e., in reflected light), one can judge the structure of the test sample, which is used in histochemistry, histology, microbiology, and immunological studies. Direct staining with luminescent dyes makes it possible to more clearly identify cell structures that are difficult to see in a light microscope.

X-ray microscope used to study objects in X-rays, therefore, such microscopes are equipped with a microfocus X-ray source of radiation, an X-ray image-to-visible converter - an electron-optical converter that forms a visible image on an oscilloscope tube or on photographic film. X-ray microscopes have a linear resolution of up to 0.1 µm, which makes it possible to study the fine structures of living matter.

Electron microscope designed to study ultrafine structures that are indistinguishable in light microscopes. Unlike light, in an electron microscope, resolution is determined not only by diffraction phenomena, but also by various aberrations of electronic lenses, which are almost impossible to correct. The aiming of the microscope is mainly carried out by diaphragming due to the use of small apertures of electron beams.

2.1 Historical background

The property of a system of two lenses to give enlarged images of objects was already known in the 16th century. in the Netherlands and northern Italy to craftsmen who made spectacle lenses. There is evidence that around 1590 an instrument of the M type was built by Z. Jansen (Netherlands). The rapid spread of M. and their improvement, mainly by optician artisans, begins from 1609–10, when G. Galileo, studying the telescope he designed (see. Spotting Scope), used it as M., changing the distance between the lens and eyepiece. The first brilliant successes in the use of M. in scientific research are associated with the names of R. Hooke (circa 1665; in particular, he established that animal and plant tissues have a cellular structure) and especially A. Leeuwenhoek, who discovered microorganisms with the help of M. (1673-- 77). At the beginning of the 18th century M. appeared in Russia: here L. Euler (1762; Dioptrics, 1770–71) developed methods for calculating the optical units of M. In 1827, J. B. Amici was the first to use an immersion lens in M.. In 1850, the English optician G. Sorby created the first microscope for observing objects in polarized light.

Wide development of methods of microscopic researches and improvement of various types of M. in 2nd half of 19 and in 20 centuries. The scientific activity of E. Abbe, who developed (1872–73) the classical theory of the formation of images of non-luminous objects in M., contributed significantly to the scientific activity. In 1893, the English scientist J. Sirks laid the foundation for interference microscopy. In 1903, the Austrian researchers R. Zigmondy and G. Siedentopf created the so-called. ultramicroscope. In 1935, F. Zernike proposed the phase contrast method for observing transparent objects that weakly scatter light in M.. A great contribution to the theory and practice of microscopy was made by owls. scientists - L. I. Mandelstam, D. S. Rozhdestvensky, A. A. Lebedev, V. P. Linnik.

2.2 The main components of the microscope

In most types of M. (with the exception of inverted ones, see below), a device for attaching lenses is located above the object table on which the preparation is fixed, and a condenser is installed under the table. Any M. has a tube (tube) in which eyepieces are installed; Mechanisms for coarse and fine focusing (carried out by changing the relative position of the preparation, objective, and eyepiece) are also an obligatory accessory of M.. All these nodes are mounted on a tripod or M body.

The type of condenser used depends on the choice of observation method. Bright-field condensers and condensers for observation by the method of phase or interference contrast are two- or three-lens systems that differ greatly from one another. For bright-field condensers, the numerical aperture can reach 1.4; they include an aperture iris diaphragm, which can sometimes be shifted to the side to obtain oblique illumination of the preparation. Phase-contrast condensers are equipped with annular diaphragms. Complex systems of lenses and mirrors are dark-field condensers. A separate group consists of epicondensers, which are necessary when observing by the dark field method in reflected light, a system of annular lenses and mirrors installed around the lens. In UV microscopy, special mirror-lens and lens condensers are used, which are transparent to ultraviolet rays.

The lenses in most modern microscopes are interchangeable and are selected depending on the specific conditions of observation. Often several lenses are fixed in one rotating (so-called revolving) head; lens change in this case is carried out by simply turning the head. According to the degree of correction of chromatic aberration (see Chromatic aberration), microlenses are distinguished Achromats and apochromats (see Achromat). The first are the simplest in design; chromatic aberration in them is corrected for only two wavelengths, and the image remains slightly colored when the object is illuminated with white light. In apochromats, this aberration is corrected for three wavelengths, and they give colorless images. The image plane of achromats and apochromats is somewhat curved (see Curvature of the field). The accommodation of the eye and the ability to view the entire field of view with the help of refocusing M. partly compensate for this shortcoming in visual observation, but it greatly affects microphotography - the extreme parts of the image are blurred. Therefore, microobjectives with additional field curvature correction are widely used - planachromats and planapochromats. In combination with conventional lenses, special projection systems are used - gomals, inserted instead of eyepieces and correcting the curvature of the image surface (they are unsuitable for visual observation).

In addition, microobjectives differ: a) in terms of spectral characteristics - for lenses for the visible region of the spectrum and for UV and IR microscopy (lens or mirror-lens); b) along the length of the tube for which they are designed (depending on the design of the M.), - for lenses for a tube of 160 mm, for a tube of 190 mm and for the so-called. "the length of the tube is infinity" (the latter create an image "at infinity" and are used in conjunction with an additional - the so-called tube - lens, which translates the image into the focal plane of the eyepiece); c) according to the medium between the lens and the preparation - into dry and immersion; d) according to the method of observation - into ordinary, phase-contrast, interference, etc.; e) by type of preparations - for preparations with and without a cover slip. A separate type are epi lenses (a combination of a conventional lens with an epicondenser). The variety of lenses is due to the variety of methods of microscopic observation and the design of microscopes, as well as differences in the requirements for correcting aberrations under different working conditions. Therefore, each lens can only be used in the conditions for which it was designed. For example, a lens designed for a 160 mm tube cannot be used in an M. with a tube length of 190 mm; With a cover slip slide lens, slides without a cover slip cannot be observed. It is especially important to observe the design conditions when working with dry lenses of large apertures (A > 0.6), which are very sensitive to any deviations from the norm. The thickness of the coverslips when working with these objectives should be equal to 0.17 mm. An immersion lens can only be used with the immersion for which it was designed.

The type of eyepiece used for this method of observation is determined by the choice of the M objective. compensation eyepieces calculated so that their residual chromatic aberration is of a different sign than that of lenses, which improves image quality. In addition, there are special photo eyepieces and projection eyepieces that project an image onto a screen or photographic plate (this also includes the gomals mentioned above). A separate group consists of quartz eyepieces that are transparent to UV rays.

Various accessories to M. allow to improve conditions of supervision and to expand possibilities of researches. Illuminators of various types are designed to create the best lighting conditions; ocular micrometers (see Ocular micrometer) are used to measure the size of objects; binocular tubes make it possible to observe the drug simultaneously with both eyes; microphoto attachments and microphoto setups are used for microphotography; drawing devices make it possible to sketch images. For quantitative studies, special devices are used (for example, microspectrophotometric nozzles).

2.3 Types of microscopes

The design of an M., its equipment, and the characteristics of its main units are determined either by the field of application, the range of problems, and the nature of the objects for which it is intended, or by the method (methods) of observation for which it is designed, or by both. All this led to the creation of various types of specialized metrics, which make it possible to study strictly defined classes of objects (or even only some of their specific properties) with high accuracy. On the other hand, there are so-called. universal M., with the help of which it is possible to observe various objects by various methods.

Biological M. are among the most common. They are used for botanical, histological, cytological, microbiological, and medical research, as well as in areas not directly related to biology—to observe transparent objects in chemistry, physics, and so on. There are many models of biological M. that differ in their constructive design and accessories that significantly expand the range of objects under study. These accessories include: replaceable illuminators for transmitted and reflected light; replaceable condensers for work on methods of bright and dark fields; phase contrast devices; ocular micrometers; microphoto attachments; sets of light filters and polarizing devices, which make it possible to use the technique of luminescent and polarizing microscopy in ordinary (non-specialized) M.. In auxiliary equipment for biological M., a particularly important role is played by the means of microscopic technology (see Microscopic technology), designed to prepare preparations and perform various operations with them, including directly during the observation process (see Micromanipulator, Microtome).

Biological research microscopes are equipped with a set of interchangeable lenses for various conditions and methods of observation and types of specimens, including epi-objectives for reflected light and often phase-contrast lenses. A set of objectives corresponds to a set of eyepieces for visual observation and microphotography. Usually such M. have binocular tubes for observation with two eyes.

In addition to general-purpose M., various M., specialized in the method of observation, are also widely used in biology (see below).

Inverted microscopes are distinguished by the fact that the lens in them is located under the observed object, and the condenser is on top. The direction of the path of the rays passing from top to bottom through the lens is changed by a system of mirrors, and they fall into the eye of the observer, as usual, from bottom to top ( rice. eight). M. of this type are intended for the study of bulky objects that are difficult or impossible to place on the object tables of conventional M. In biology, with the help of such M., tissue cultures in a nutrient medium are studied, which are placed in a thermostatic chamber to maintain a given temperature. Inverted meters are also used to study chemical reactions, determine the melting points of materials, and in other cases when cumbersome auxiliary equipment is required to carry out the observed processes. Inverted microscopes are equipped with special devices and cameras for microphotography and film microfilming.

The scheme of an inverted microscope is especially convenient for observing the structures of various surfaces in reflected light. Therefore, it is used in most metallographic M. In them, the sample (section of metal, alloy or mineral) is installed on the table with the polished surface down, and the rest of it can have an arbitrary shape and does not require any processing. There are also metallographic M., in which the object is placed from below, fixing it on a special plate; the mutual position of nodes in such meters is the same as in ordinary (non-inverted) meters. The surface under study is often preliminarily etched, so that the grains of its structure become sharply distinguishable from each other. In M. of this type, you can use the bright field method with direct and oblique illumination, the dark field method, and observation in polarized light. When working in a bright field, the lens simultaneously serves as a condenser. For dark-field illumination mirror parabolic epicondensers are used. The introduction of a special auxiliary device makes it possible to carry out phase contrast in metallographic M. with a conventional lens ( rice. 9).

Luminescent microscopes are equipped with a set of interchangeable light filters, by selecting which it is possible to single out in the illuminator's radiation a part of the spectrum that excites the luminescence of a particular object under study. A light filter is also selected that transmits only luminescence light from the object. The glow of many objects is excited by UV rays or the short-wavelength part of the visible spectrum; therefore, the sources of light in luminescent lamps are ultrahigh-pressure mercury lamps that give just such (and very bright) radiation (see Gas-discharge light sources). In addition to special models of luminescent lamps, there are luminescent devices used in conjunction with conventional lamps; they contain an illuminator with a mercury lamp, a set of light filters, etc. opaque illuminator for illumination of preparations from above.

Ultraviolet and infrared microscopes are used for research in regions of the spectrum invisible to the eye. Their fundamental optical schemes are similar to those of conventional MMs. Because of the great difficulty in correcting aberrations in the UV and IR regions, the condenser and objective in such MMs often represent mirror-lens systems in which chromatic aberration is significantly reduced or completely absent. Lenses are made of materials that are transparent to UV (quartz, fluorite) or IR (silicon, germanium, fluorite, lithium fluoride) radiation. Ultraviolet and infrared M. are supplied with cameras in which the invisible image is fixed; visual observation through an eyepiece in ordinary (visible) light serves, when possible, only for preliminary focusing and orientation of the object in the field of view of the M. As a rule, these M. have electron-optical converters that convert an invisible image into a visible one.

Polarizing meters are designed to study (with the help of optical compensators) changes in the polarization of light that has passed through an object or reflected from it, which opens up possibilities for quantitative or semi-quantitative determination of various characteristics of optically active objects. The nodes of such M. are usually made in such a way as to facilitate accurate measurements: the eyepieces are supplied with a crosshair, a micrometer scale or a grid; a rotating object table -- with a goniometric limb for measuring the angle of rotation; often a Fedorov table is attached to the object table (see Fedorov table), which makes it possible to arbitrarily rotate and tilt the specimen to find the crystallographic and crystal-optical axes. The lenses of polarizing lenses are specially selected so that there are no internal stresses in their lenses that lead to the depolarization of light. In M. of this type, there is usually an auxiliary lens (the so-called Bertrand lens) that can be turned on and off, which is used for observations in transmitted light; it allows one to consider interference patterns (see Crystal optics) formed by light in the rear focal plane of the objective after passing through the crystal under study.

With the help of interference microscopes, transparent objects are observed using the method of interference contrast; many of them are structurally similar to conventional M., differing only in the presence of a special condenser, objective and measuring unit. If the observation is made in polarized light, then such microscopes are supplied with a polarizer and an analyzer. By area of ​​application (mainly biological research), these M. can be attributed to specialized biological M. Interferometric M. often also include microinterferometers - M. of a special type used to study the microrelief of the surfaces of machined metal parts.

Stereomicroscopes. The binocular tubes used in conventional microscopes, despite the convenience of observing with two eyes, do not produce a stereoscopic effect: in this case, the same rays enter both eyes at the same angles, only they are divided into two beams by a prism system. Stereomicroscopes, which provide a truly three-dimensional perception of a microobject, are in fact two microscopes made in the form of a single structure so that the right and left eyes observe the object at different angles ( rice. 10). Such M. are most widely used where it is required to perform any operations with an object in the course of observation (biological research, surgical operations on blood vessels, the brain, in the eye - Micrurgy, the assembly of miniature devices, such as Transistors), - stereoscopic perception facilitates these operations. Convenience of orientation in the field of view of M. is also included in its optical scheme of prisms that play the role of turning systems (see Turning system); the image in such M. is straight, not inverted. So how is the angle between the optical axes of lenses in stereo microscopes usually? 12°, their numerical aperture, as a rule, does not exceed 0.12. Therefore, a useful increase in such M. is no more than 120.

Comparison lenses consist of two structurally combined ordinary lenses with a single ocular system. The observer sees images of two objects at once in two halves of the field of view of such a lens, which makes it possible to directly compare them in terms of color, structure, distribution of elements, and other characteristics. Comparison markers are widely used in assessing the quality of surface treatment, determining grade (comparison with a reference sample), etc. Special markers of this type are used in criminology, in particular, to identify the weapon from which the bullet under study was fired.

In television M., working according to the scheme of microprojection, the image of the preparation is converted into a sequence of electrical signals, which then reproduce this image on an enlarged scale on the screen of a cathode ray tube (see. Cathode ray tube) (kinescope). In such M., it is possible, by purely electronic means, by changing the parameters of the electrical circuit through which the signals pass, to change the contrast of the image and to adjust its brightness. Electrical amplification of signals allows images to be projected onto a large screen, while conventional micro-projection requires extremely strong illumination, often harmful to microscopic objects. The great advantage of television meters is that they can be used to remotely study objects whose proximity is dangerous for the observer (for example, radioactive).

In many studies, it is necessary to count microscopic particles (for example, bacteria in colonies, aerosols, particles in colloidal solutions, blood cells, etc.), determine the areas occupied by grains of the same kind in thin sections of an alloy, and produce other similar measurements. The transformation of images in television meters into a series of electrical signals (pulses) made it possible to build automatic counters of microparticles that register them by the number of pulses.

The purpose of measuring meters is to accurately measure the linear and angular dimensions of objects (often not at all small). According to the method of measurement, they can be divided into two types. Measuring M. of the 1st type are used only in cases where the measured distance does not exceed the linear dimensions of the field of view of the M. In such M. directly (using a scale or a screw ocular micrometer (see Ocular micrometer)) is measured not the object itself, but its image in the focal plane of the eyepiece, and only then, according to the known value of the lens magnification, the measured distance on the object is calculated. Often, in these microscopes, the images of objects are compared with exemplary profiles printed on the plates of interchangeable eyepiece heads. In the measuring The 2nd type of the subject table with the object and the M.'s body can be moved relative to each other with the help of precise mechanisms (more often - the table relative to the body); by measuring this movement with a micrometric screw or a scale rigidly fastened to the object stage, the distance between the observed elements of the object is determined. There are measuring meters for which measurements are made in only one direction (single-coordinate meters). Much more common are M. with movements of the object table in two perpendicular directions (limits of movement up to 200-500 mm); For special purposes, M. are used, in which measurements (and, consequently, the relative movements of the table and body of the M.) are possible in three directions corresponding to three axes of rectangular coordinates. On some M. it is possible to carry out measurements in polar coordinates; for this, the object table is made rotating and equipped with a scale and a Nonius for reading the rotation angles. The most accurate measuring instruments of the second type use glass scales, and readings on them are carried out using an auxiliary (so-called reading) microscope (see below). The accuracy of measurements in M. of the 2nd type is much higher compared to M. of the 1st type. In the best models, the accuracy of linear measurements is usually of the order of 0.001 mm, the accuracy of measuring angles is of the order of 1 ". Measuring meters of the 2nd type are widely used in industry (especially in mechanical engineering) for measuring and controlling the dimensions of machine parts, tools, etc.

In devices for especially precise measurements (for example, geodetic, astronomical, etc.), readings on linear scales and divided circles of goniometric instruments are made using special reading meters - scale meters and micrometers. The first has an auxiliary glass scale. By adjusting the magnification of the objective lens, its image is made equal to the observed interval between divisions of the main scale (or circle), after which, by counting the position of the observed division between the strokes of the auxiliary scale, it can be directly determined with an accuracy of about 0.01 of the interval between divisions. The accuracy of readings (on the order of 0.0001 mm) is even higher in M. micrometers, in the ocular part of which a thread or spiral micrometer is placed. The magnification of the lens is adjusted so that the movement of the thread between the images of the strokes of the measured scale corresponds to an integer number of turns (or half turns) of the micrometer screw.

In addition to those described above, there are a significant number of still more narrowly specialized types of thermometers, for example, thermometers for counting and analyzing traces of elementary particles and nuclear fission fragments in nuclear photographic emulsions (see Nuclear photographic emulsion), high-temperature meters for studying objects heated to temperatures of the order of 2000 ° C, contact lenses for studying the surfaces of living organs of animals and humans (the lens in them is pressed close to the surface under study, and the lens is focused by a special built-in system).

Conclusion

What can we expect from the microscopy of tomorrow? What problems can be expected to be solved? First of all - distribution to more and more new objects. The achievement of atomic resolution is certainly the greatest achievement of scientific and technical thought. However, let's not forget that this achievement extends only to a limited range of objects, which are also placed in very specific, unusual and highly influencing conditions. Therefore, it is necessary to strive to extend atomic resolution to a wide range of objects.

Over time, we can expect other charged particles to “work” in microscopes. It is clear, however, that this must be preceded by the search for and development of powerful sources of such particles; in addition, the creation of a new type of microscope will be determined by the emergence of specific scientific problems, to the solution of which these new particles will make a decisive contribution.

Microscopic studies of processes in dynamics will be improved, i.e. occurring directly in the microscope or in devices articulated with it. Such processes include testing samples in a microscope (heating, stretching, etc.) directly during the analysis of their microstructure. Here, success will be due, first of all, to the development of high-speed photography technology and an increase in the temporal resolution of detectors (screens) of microscopes, as well as the use of powerful modern computers.

List of used literature

1. Small medical encyclopedia. -- M.: Medical Encyclopedia. 1991--96

2. First aid. -- M.: Great Russian Encyclopedia. 1994

3. Encyclopedic dictionary of medical terms. -- M.: Soviet Encyclopedia. -- 1982--1984

4. http://dic.academic.ru/

5. http://ru.wikipedia.org/

6. www.golkom.ru

7. www.avicenna.ru

8. www.bionet.nsc.ru

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Everyone knows that biology is the science of life. At present, it represents the totality of the sciences of living nature. Biology studies all manifestations of life: the structure, functions, development and origin of living organisms, their relationships in natural communities with the environment and with other living organisms.
Since man began to realize his difference from the animal world, he began to study the world around him. At first, his life depended on it. Primitive people needed to know which living organisms can be eaten, used as medicines, for making clothes and dwellings, and which of them are poisonous or dangerous.
With the development of civilization, a person could afford such a luxury as doing science for educational purposes.
Studies of the culture of ancient peoples have shown that they had extensive knowledge about plants and animals and widely used them in everyday life.?

Modern biology is a complex science, which is characterized by the interpenetration of ideas and methods of various biological disciplines, as well as other sciences, primarily physics, chemistry, and mathematics.

The main directions of development of modern biology. Currently, three directions in biology can be conditionally distinguished.
First, it is classical biology. It is represented by natural scientists who study the diversity of wildlife. They objectively observe and analyze everything that happens in wildlife, study living organisms and classify them. It is wrong to think that in classical biology all discoveries have already been made. In the second half of the XX century. not only many new species have been described, but also large taxa have been discovered, up to kingdoms (Pogonophores) and even superkingdoms (Archaebacteria, or Archaea). These discoveries forced scientists to take a fresh look at the entire history of the development of wildlife. For true natural scientists, nature is a value in itself. Every corner of our planet is unique for them. That is why they are always among those who acutely feel the danger to the nature around us and actively advocate for it.
The second direction is evolutionary biology. In the 19th century, the author of the theory of natural selection, Charles Darwin, began as an ordinary naturalist: he collected, observed, described, traveled, revealing the secrets of wildlife. However, the main result of his work, which made him a famous scientist, was a theory explaining organic diversity.

Currently, the study of the evolution of living organisms is actively continuing. The synthesis of genetics and evolutionary theory led to the creation of the so-called synthetic theory of evolution. But even now there are still many unresolved questions that evolutionary scientists are looking for answers to.

Created at the beginning of the 20th century. by our outstanding biologist Alexander Ivanovich Oparin, the first scientific theory of the origin of life was purely theoretical. Currently, experimental studies of this problem are being actively conducted, and thanks to the use of advanced physicochemical methods, important discoveries have already been made and new interesting results can be expected.
New discoveries made it possible to supplement the theory of anthropogenesis. But the transition from the animal world to man still remains one of the biggest mysteries of biology.
The third direction is physicochemical biology, which studies the structure of living objects using modern physical and chemical methods. This is a rapidly developing area of ​​biology, important both in theoretical and practical terms. We can say with confidence that new discoveries are waiting for us in physical and chemical biology, which will allow us to solve many problems facing humanity,

The development of biology as a science. Modern biology is rooted in antiquity and is associated with the development of civilization in the Mediterranean countries. We know the names of many outstanding scientists who contributed to the development of biology. Let's name just a few of them.

Hippocrates (460 - c. 370 BC) gave the first relatively detailed description of the structure of man and animals, pointed out the role of the environment and heredity in the occurrence of diseases. He is considered the founder of medicine.
Aristotle (384-322 BC) divided the surrounding world into four kingdoms: the inanimate world of earth, water and air; plant world; the animal world and the human world. He described many animals, laid the foundation for taxonomy. The four biological treatises he wrote contained almost all the information about animals known by that time. The merits of Aristotle are so great that he is considered the founder of zoology.
Theophrastus (372-287 BC) studied plants. He described more than 500 species of plants, gave information about the structure and reproduction of many of them, put into use many botanical terms. He is considered the founder of botany.
Gaius Pliny the Elder (23-79) collected information about living organisms known by that time and wrote 37 volumes of the encyclopedia Natural History. Almost until the Middle Ages, this encyclopedia was the main source of knowledge about nature.

Claudius Galen made extensive use of dissections of mammals in his scientific research. He was the first to make comparative

anatomical description of man and monkey. Studied the central and peripheral nervous system. Historians of science consider him the last great biologist of antiquity.
In the Middle Ages, religion was the dominant ideology. Like other sciences, biology during this period had not yet emerged as an independent field and existed in the general mainstream of religious and philosophical views. And although the accumulation of knowledge about living organisms continued, one can speak of biology as a science in that period only conditionally.
The Renaissance is a transitional period from the culture of the Middle Ages to the culture of modern times. The fundamental socio-economic transformations of that time were accompanied by new discoveries in science.
The most famous scientist of this era, Leonardo da Vinci (1452-1519), made a certain contribution to the development of biology.

He studied the flight of birds, described many plants, ways of connecting bones in the joints, the activity of the heart and the visual function of the eye, the similarity of the bones of humans and animals.

In the second half of the XV century. natural sciences begin to develop rapidly. This was facilitated by geographical discoveries, which made it possible to significantly expand information about animals and plants. Rapid accumulation of scientific knowledge about living organisms
led to the division of biology into separate sciences.
In the XVI-XVII centuries. Botany and zoology began to develop rapidly.
The invention of the microscope (early 17th century) made it possible to study the microscopic structure of plants and animals. Microscopically small living organisms, bacteria and protozoa, invisible to the naked eye, were discovered.
A great contribution to the development of biology was made by Carl Linnaeus, who proposed a classification system for animals and plants.
Karl Maksimovich Baer (1792-1876) in his works formulated the main provisions of the theory of homologous organs and the law of germinal similarity, which laid the scientific foundations of embryology.

In 1808, in his work "Philosophy of Zoology", Jean-Baptiste Lamarck raised the question of the causes and mechanisms of evolutionary transformations and outlined the first theory of evolution in time.

The cell theory played a huge role in the development of biology, which scientifically confirmed the unity of the living world and served as one of the prerequisites for the emergence of Charles Darwin's theory of evolution. The zoologist Theodor Schwann (1818-1882) and the botanist Matthias Jakob Schleiden (1804-1881) are considered the authors of the cell theory.

Based on numerous observations, Charles Darwin published in 1859 his main work "On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Breeds in the Struggle for Life." In it, he formulated the main provisions of the theory of evolution, proposed the mechanisms of evolution and ways of evolutionary transformations of organisms.

The 20th century began with the rediscovery of Gregor Mendel's laws, which marked the beginning of the development of genetics as a science.
In the 40-50s of the XX century. ideas and methods of physics, chemistry, mathematics, cybernetics, and other sciences began to be widely used in biology, and microorganisms were used as objects of study. As a result, biophysics, biochemistry, molecular biology, radiation biology, bionics, etc. emerged and rapidly developed as independent sciences. Space exploration contributed to the birth and development of space biology.

In the XX century. a direction of applied research appeared - biotechnology. This direction will undoubtedly develop rapidly in the 21st century. You will learn more about this direction in the development of biology when studying the chapter "Fundamentals of Breeding and Biotechnology".

Currently, biological knowledge is used in all spheres of human activity: in industry and agriculture, medicine and energy.
Ecological research is extremely important. We finally began to realize that the fragile balance that exists on our small planet is easy to destroy. Mankind has faced a daunting task - the preservation of the biosphere in order to maintain the conditions for the existence and development of civilization. It is impossible to solve it without biological knowledge and special studies. Thus, at present, biology has become a real productive force and a rational scientific basis for the relationship between man and nature.

First microscopists second half of the 17th century. - physicist R. Hooke, anatomist M. Malpighi, botanist N. Gru, amateur optician A. Leeuwenhoek and others described the structure of the skin, spleen, blood, muscles, seminal fluid, etc. using a microscope. Each study was essentially a discovery, which did not get along well with the metaphysical view of nature that has evolved over the centuries. The random nature of the discoveries, the imperfection of microscopes, the metaphysical worldview did not allow for 100 years (from the middle of the 17th century to the middle of the 18th century) to make significant steps forward in the knowledge of the laws of the structure of animals and plants, although attempts were made to generalize (theories of "fibrous" and " granular structure of organisms, etc.).

The discovery of the cellular structure occurred at a time in the development of mankind, when experimental physics began to claim to be called the mistress of all sciences. In London, a society of the greatest scientists was created, who focused on improving the world on specific physical laws. At the meetings of the community members, there were no political debates, only various experiments were discussed and research on physics and mechanics was shared. Times were turbulent then, and scientists observed very strict secrecy. The new community began to be called the "college of the invisible." The first who stood at the origins of the creation of the society was Robert Boyle, Hooke's great mentor. The Board produced the necessary scientific literature. The author of one of the books was Robert Hook, who was also a member of this secret scientific community. Hooke already in those years was known as the inventor of interesting devices that made it possible to make great discoveries. One of these devices was microscope.

One of the first creators of the microscope was Zacharius Jansen who created it in 1595. The idea of ​​the invention was that two lenses (convex) were mounted inside a special tube with a retractable tube to focus the image. This device could increase the studied objects by 3-10 times. Robert Hooke improved this product, which played a major role in the upcoming discovery.

Robert Hooke for a long time observed various small specimens through the created microscope, and once he took an ordinary stopper from a vessel for viewing. Having examined a thin section of this cork, the scientist was surprised at the complexity of the structure of the substance. An interesting pattern of many cells appeared to his eyes, surprisingly similar to a honeycomb. Since cork is a vegetable product, Hooke began to study sections of plant stems with a microscope. Everywhere a similar picture was repeated - a set of honeycombs. The microscope showed many rows of cells, which were separated by thin walls. Robert Hooke called these cells cells. Subsequently, a whole science of cells was formed, which is called cytology. Cytology includes the study of the structure of cells and their vital activity. This science is used in many areas, including medicine and industry.

With name M. Malpighi This outstanding biologist and physician is associated with an important period of microscopic studies of the anatomy of animals and plants.
The invention and improvement of the microscope allowed scientists to discover
a world of extremely small creatures, completely different from those
which are visible to the naked eye. Having received a microscope, Malpighi made a number of important biological discoveries. At first he considered
everything that came to hand:

• insects,
• light frogs,
• blood cells,
• capillaries,
• skin,
• liver,
• spleen
• plant tissues.

In the study of these subjects, he reached such perfection that he became
one of the founders of microscopic anatomy. Malpighi was the first to use
microscope for the study of blood circulation.

Using a 180x magnification, Malpighi made a discovery in the theory of blood circulation: looking at a frog lung preparation under a microscope, he noticed air bubbles surrounded by a film, and small blood vessels, saw an extensive network of capillary vessels connecting arteries to veins (1661). Over the next six years, Malpighi made observations that he described in scientific works that brought him fame as a great scientist. Malpighi's reports on the structure of the brain, tongue, retina, nerves, spleen, liver, skin, and on the development of the embryo in a chicken egg, as well as on the anatomical structure of plants, testify to very careful observations.

Nehemiah Gru(1641 - 1712). English botanist and physician, microscopist,

founder of plant anatomy. The main works are devoted to the issues of structure and gender of plants. Along with M. Malpighi was the founder

plant anatomy. First described:

• stomata,
• radial arrangement of xylem in roots,
• morphology of vascular tissue in the form of a dense formation in the center of the stem of a young plant,
• the process of forming a hollow cylinder in old stems.

He introduced the term "comparative anatomy", introduced the concepts of "tissue" and "parenchyma" into botany. Studying the structure of flowers, I came to the conclusion that they are the organs of fertilization in plants.

Leeuwenhoek Anthony(October 24, 1632–August 26, 1723), Dutch naturalist. He worked in a textile shop in Amsterdam. Back in Delft, in his spare time he worked as a lens grinder. In total, during his life, Leeuwenhoek made about 250 lenses, achieving a 300-fold increase and achieved great perfection in this. The lenses he made, which he inserted into metal holders with a needle attached to them to put the object of observation, gave a 150-300-fold magnification. With the help of such "microscopes" Leeuwenhoek first observed and sketched:

• spermatozoa (1677),
• bacteria (1683),
• erythrocytes,
• protozoa,
• individual plant and animal cells,
• eggs and fetuses
• muscle tissue,
• many other parts and organs of more than 200 species of plants and animals.

First described parthenogenesis in aphids (1695–1700).

Leeuwenhoek stood on the positions of preformism, arguing that the formed embryo is already contained in the "animalcule" (spermatozoon). He denied the possibility of spontaneous generation. He described his observations in letters (up to 300 in total), which he sent mainly to the Royal Society of London. Following the movement of blood through the capillaries, he showed that capillaries connect arteries and veins. For the first time he observed erythrocytes and found that in birds, fish and frogs they have an oval shape, while in humans and other mammals they are disc-shaped. He discovered and described rotifers and a number of other small freshwater organisms.

The use of an achromatic microscope in scientific research has served as a new impetus for the development of histology. At the beginning of the XIX century. the first image of plant cell nuclei was made. J. Purkinje(in 1825-1827) described the nucleus in the ovum of a chicken, and then the nuclei in the cells of various animal tissues. Later, he introduced the concept of "protoplasm" (cytoplasm) of cells, characterized the shape of nerve cells, the structure of glands, etc.

R. Brown concluded that the nucleus is an essential part of the plant cell. Thus, gradually began to accumulate material on the microscopic organization of animals and plants and the structure of "cells" (cellula), seen for the first time by R. Hooke.

The creation of the cell theory had a huge progressive impact on the development of biology and medicine. In the middle of the XIX century. began a period of rapid development of descriptive histology. Based on the cellular theory, the composition of various organs and tissues and their development were studied, which made it possible even then to create a microscopic anatomy in basic terms and to refine the classification of tissues, taking into account their microscopic structure (A. Kölliker and others).