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A brief history of the development of biology. Microscope and its applications The significance of the invention of the microscope

The World History
05.07.2020

Today, the microscope is one of the most important instruments that is used in many branches of science.

Microscope - (from the Greek mikros - small and skopeo - look), an optical device for obtaining an enlarged image of small objects and their details invisible to the naked eye.

It is difficult to name the first who invented the microscope, because these devices began to appear in the 16th century. different countries and cities.

Microscope and its applications

In 1595 by Zacharius Jansen. It was Jansen who connected two convex lenses inside a tube. The magnification of that microscope ranged from 3 to 10 times. Also in 1590, the microscope appeared with John Lippershey, who had previously designed a simple telescope. In 1624, Galileo Galilei presented his telescope (he called his device (occhiolino Italian - small eye).

In Holland in the 17th century, Anthony Van Leeuwenhoek created the basic prototype of the modern microscope. The most interesting thing is that Leeuwenhoek was not a scientist. The talented self-taught man worked as a textile merchant. The first thing he looked at through the device he created was a drop of water, in which he saw many small organisms, which he called animalculus (Latin for “little animals”). But he didn't stop there. After all, it was Van Leeuwenhoek who discovered the cellular structure of living tissue by looking at sections of vegetables, fruits and meat.

For his discovery and for his achievements, in 1680 Leeuwenhoek was elected a full member of the Royal Society, and a little later became an academician of the French Academy of Sciences.

The science that studies objects using a microscope is called microscopy (lat. small, small and see).

Depending on the functions they perform, microscopes are divided into:

Optical microscopes (among others, they appeared first)
- electron microscopes;
- scanning microscopes;
- X-ray microscopes;
- laser X-ray microscopes;
- differential microscopes;

Microscopes are used in the following areas:

Biological (used in biological and medical research);
- metallographic (used in industrial and scientific laboratories where opaque objects are studied);
- stereoscopic (used in laboratories and industries to enlarge objects during work operations);
- polarized (used in research laboratories for research in polarized light);

Nowadays you can buy an optical microscope without any problems.

Original news “Microscope and its application”

MICROSCOPE

REPORT on Biology for a 6th grade student

For a long time, man lived surrounded by invisible creatures, used the products of their vital activity (for example, when baking bread from sour dough, preparing wine and vinegar), suffered when these creatures caused illness or spoiled food supplies, but was not aware of their presence . I didn’t suspect because I didn’t see, and I didn’t see because the size of these micro creatures lay much below the limit of visibility of which the human eye is capable. It is known that a person with normal vision at an optimal distance (25-30 cm) can distinguish an object measuring 0.07–0.08 mm in the form of a point. A person cannot notice smaller objects. This is determined by the structural features of his organ of vision.

Around the same time that space exploration with telescopes began, the first attempts were made to reveal the mysteries of the microworld using lenses. Thus, during archaeological excavations in Ancient Babylon, biconvex lenses were found - the simplest optical instruments. The lenses were made from polished rock crystal We can consider that with their invention, man took the first step on the path to the microworld.


The simplest way To enlarge an image of a small object is to observe it with a magnifying glass. A magnifying glass is a converging lens with a small focal length (usually no more than 10 cm) inserted into the handle.


Telescope creator Galileo V 1610 year, he discovered that when greatly extended, his telescope made it possible to greatly magnify small objects. It can be considered inventor of the microscope consisting of positive and negative lenses.
A more advanced tool for observing microscopic objects is simple microscope. It is not known exactly when these devices appeared. At the very beginning of the 17th century, several such microscopes were made by a spectacle maker. Zachariah Jansen from Middelburg.

In the essay A. Kircher, published in 1646 year, contains a description simple microscope, named by him "flea glass". It consisted of a magnifying glass embedded in a copper base, on which an object table was mounted, which served to place the object in question; at the bottom there was a flat or concave mirror that reflected the sun's rays onto the object and thus illuminated it from below. The magnifying glass was moved by means of a screw to the stage until the image became clear and distinct.

First outstanding discoveries were made just using a simple microscope. In the middle of the 17th century, the Dutch naturalist achieved brilliant success Anthony Van Leeuwenhoek. Over the years, Leeuwenhoek perfected his ability to make tiny (sometimes less than 1 mm in diameter) biconvex lenses, which he made from a small glass ball, in turn obtained by melting a glass rod in a flame. This glass bead was then ground using a primitive grinding machine. Throughout his life, Leeuwenhoek made at least 400 such microscopes. One of them, kept in the University Museum in Utrecht, gives more than 300 times magnification, which was a huge success for the 17th century.

At the beginning of the 17th century there appeared compound microscopes, composed of two lenses. The inventor of such a complex microscope is not exactly known, but many facts indicate that he was a Dutchman Cornelius Drebel, who lived in London and was in the service of the English King James I. In a compound microscope there was two glasses: one - the lens - facing the object, the other - the eyepiece - facing the eye of the observer. In the first microscopes, the lens was a biconvex glass, which gave a real, magnified, but inverted image. This image was examined with the help of an eyepiece, which thus played the role of a magnifying glass, but only this magnifying glass served to enlarge not the object itself, but its image.

IN 1663 year microscope Drebel was improved English physicist Robert Hooke, who introduced a third lens into it, called the collective. This type of microscope gained great popularity, and most microscopes of the late 17th - first half of the 8th century were built according to its design.

Microscope device


A microscope is an optical instrument designed to examine magnified images of micro-objects that are invisible to the naked eye.

The main parts of a light microscope (Fig. 1) are the lens and the eyepiece, enclosed in a cylindrical body - a tube. Most models intended for biological research are equipped with three lenses with different focal lengths and a rotating mechanism designed for quick change - a turret, often called a turret. The tube is located on the top of a massive tripod, which includes a tube holder. Just below the lens (or a turret with several lenses) there is a stage on which slides with the samples under study are mounted. Sharpness is adjusted using the coarse and fine adjustment screw, which allows you to change the position of the stage relative to the lens.


In order for the sample under study to have sufficient brightness for comfortable observation, microscopes are equipped with two more optical units (Fig. 2) - an illuminator and a condenser. The illuminator creates a stream of light that illuminates the drug being studied. In classical light microscopes, the design of the illuminator (built-in or external) involves a low-voltage lamp with a thick filament, a collecting lens and a diaphragm that changes the diameter of the light spot on the sample. The condenser, which is a collecting lens, is designed to focus the illuminator beams on the sample. The condenser also has an iris diaphragm (field and aperture), with which the light intensity is adjusted.


When working with objects that transmit light (liquids, thin sections of plants, etc.), they are illuminated with transmitted light - the illuminator and condenser are located under the object stage. Opaque samples need to be illuminated from the front. To do this, the illuminator is placed above the object stage, and its rays are directed to the object through the lens using a translucent mirror.

The illuminator can be passive, active (lamp) or consist of both elements. The simplest microscopes do not have lamps to illuminate samples. Under the table they have a two-way mirror, one side of which is flat and the other is concave. In daylight, if the microscope is placed near a window, you can get pretty good illumination using a concave mirror. If the microscope is in a dark room, they are used for illumination. flat mirror and external illuminator.

The magnification of a microscope is equal to the product of the magnification of the objective and the eyepiece. With an eyepiece magnification of 10 and an objective magnification of 40, the total magnification factor is 400. Typically, a research microscope kit includes objectives with a magnification of 4 to 100. A typical set of microscope lenses for amateur and educational research (x 4, x 10 and x 40) provides increase from 40 to 400.

Resolution – different most important characteristic microscope, which determines its quality and clarity of the image it forms. The higher the resolution, the more fine details can be seen at high magnification. In connection with resolution, they talk about “useful” and “useless” magnification. “Useful” is the maximum magnification at which maximum image detail is provided. Further magnification (“useless”) is not supported by the resolution of the microscope and does not reveal new details, but can negatively affect the clarity and contrast of the image. Thus, the limit of useful magnification of a light microscope is limited not by the general magnification factor of the objective and eyepiece - it can be made as large as desired - but by the quality of the optical components of the microscope, that is, the resolution.

The microscope includes three main functional parts:

1. Lighting part
Designed to create a light flux that allows you to illuminate an object in such a way that subsequent parts of the microscope perform their functions with extreme precision. The illuminating part of a transmitted light microscope is located behind the object under the lens in direct microscopes and in front of the object above the lens in inverted microscopes.
The lighting part includes a light source (lamp and electrical power supply) and an optical-mechanical system (collector, condenser, field and aperture adjustable/iris diaphragms).

2. Reproducing part
Designed to reproduce an object in the image plane with the image quality and magnification required for research (i.e., to construct an image that would reproduce the object as accurately as possible and in all details with the resolution, magnification, contrast and color rendition corresponding to the microscope optics).
The reproducing part provides the first stage of magnification and is located after the object to the microscope image plane. The reproducing part includes a lens and an intermediate optical system.
Modern microscopes of the latest generation are based on optical lens systems corrected for infinity.
This requires the additional use of so-called tube systems, which parallel beams The light coming out of the lens is “collected” in the microscope image plane.

3. Visualization part
Designed to obtain a real image of an object on the retina of the eye, photographic film or plate, on the screen of a television or computer monitor with additional magnification (second stage of magnification).

The visualizing part is located between the image plane of the lens and the eyes of the observer (camera, photo camera).
The imaging part includes a monocular, binocular or trinocular imaging head with an observation system (eyepieces that work like a magnifying glass).
In addition, this part includes additional magnification systems (magnification wholesaler/change systems); projection attachments, including discussion attachments for two or more observers; drawing apparatus; image analysis and documentation systems with corresponding matching elements (photo channel).

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Abstract on the topic:

Modern methods microscopic studies

Completed by a student

2nd year 12th group

Shchukina Serafima Sergeevna

Introduction

1. Types of microscopy

1.1 Light microscopy

1.2 Phase contrast microscopy

1.3 Interference microscopy

1.4 Polarization 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 Main components of the microscope

2.3 Types of microscope

Conclusion

List of used literature

Introduction

Microscopic research methods are 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 are beyond the resolution of the human eye. The basis of microscopic research methods (MMI) 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, luminescence, polarization, stereoscopic, ultraviolet, infrared microscopy. These methods are based on different properties of light. In electron microscopy, images of objects under study arise due to a directed flow of electrons.

microscopy polarizing ultraviolet

1. Types of microscopy

1.1 Light microscopy

For light microscopy and other M.M.Is based on it. in addition to the resolution of the microscope, the character and direction of the light beam, as well as the features of the object being studied, which can be transparent or opaque. Depending on the properties of the object they change physical properties light - its color and brightness related to the wavelength and amplitude, phase, plane and direction of propagation of the wave. Various microscopic systems are based on the use of these properties of light. For light microscopy, biological objects are usually stained in order to reveal certain of their properties ( rice. 1 ). In this case, the tissues must be fixed, since staining reveals certain structures only of 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, a light microscope can also study living biological objects using the method of vital microscopy. In this case, a dark-field condenser is used, which is built into the microscope.

Rice. 1. Microscopic specimen of myocardium in case of sudden death from acute coronary insufficiency: Lee staining allows to identify contractural overcontractions of myofibrils (red areas); 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 light beam depending on the characteristics of the radiation object. In this case, the length and phase of the light wave changes. The lens 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 being studied, the light rays are deflected from the translucent phase plate. As a result, a wavelength difference arises between the rays passing through the object and the rays of the background light. 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 characteristics of the phase plate.

1.3 Interference microscopy

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

1.4 Polarization microscopy

Polarization microscopy allows you to study objects of study in light formed by two beams polarized in mutually perpendicular planes, i.e., in polarized light. To do this, film polaroids or Nicolas prisms are used, which are placed in a microscope between the light source and the preparation. Polarization changes as light rays pass (or reflect) through various structural components of cells and tissues, the properties of which are heterogeneous. In so-called isotropic structures, the speed of propagation of polarized light does not depend on the plane of polarization; in anisotropic structures, the speed of its propagation varies depending on the direction of light along the longitudinal or normal light path.

Rice. 2a). Microscopic specimen of the myocardium in the polarized transverse axis of the object.

If the refractive index of light along the structure is greater than in the transverse direction, positive birefringence occurs; in the opposite relationship, negative birefringence occurs. Many biological objects have strict molecular orientation, are anisotropic, and exhibit positive birefringence of light. Myofibrils, cilia of the ciliated epithelium, neurofibrils, collagen fibers, etc. have such properties. Comparison of the nature of refraction of polarized light rays and the magnitude of anisotropy of an object allows one to judge the molecular organization of its structure ( Fig.2 ).Polarization microscopy is one of the histological research methods, a method microbiological diagnostics, finds application in cytological studies, etc. In this case, both stained and unstained and unfixed, so-called native preparations of tissue sections can be examined in polarized light.

Rice. 2b). Microscopic specimen of the myocardium in polarized light during sudden death from acute coronary insufficiency—areas are revealed in which there is no characteristic transverse striation of cardiomyocytes; Ch400.

1.5 Fluorescence microscopy

Fluorescent microscopy is widely used. It is based on the property of some substances to produce glow - luminescence in UV rays or in the blue-violet part of the spectrum. Many biological substances such as simple proteins, coenzymes, some vitamins and medicines, have their own (primary) luminescence. Other substances begin to glow only when special dyes are added to them - fluorochromes (secondary luminescence). Fluorochromes can be distributed diffusely in the cell or selectively stain individual cellular structures or certain chemical compounds biological object. This is the basis for the use of fluorescent microscopy in cytological and histochemical studies. Using 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, fluorescent microscopy is used in the laboratory diagnosis of infections such as herpes, mumps, viral hepatitis, influenza, etc., and is used in the express diagnosis of respiratory viral infections, examining prints from the nasal mucosa of patients, and in the differential diagnosis of various infections. In pathomorphology, using fluorescent 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, fluorescence microscopy.

1.6 Ultraviolet microscopy

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

1.7 Infrared microscopy

Infrared microscopy allows you to examine objects that are opaque to visible light and UV radiation by absorbing light with a wavelength of 750-1200 nm into their structures. Infrared microscopy does not require preliminary chemical preparation. drug processing. This type of M. m. and. most often used in zoology, anthropology, and other branches of biology. In medicine, infrared microscopy is used mainly in neuromorphology and ophthalmology.

1.8 Stereoscopic microscopy

Stereoscopic microscopy is used to study three-dimensional objects. The design of stereoscopic microscopes allows you to see the object of study with the right and left eyes from different angles. They examine opaque objects at a relatively low magnification (up to 120 times). Stereoscopic microscopy is used in microsurgery, in pathomorphology for the special study of biopsy, surgical and sectional material, and 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 us to move to a qualitatively new level of studying matter. It has found wide application in morphology, microbiology, virology, biochemistry, oncology, genetics, and immunology. A sharp increase in the resolution of the electron microscope is ensured 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), deflecting 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 ), when scanning - volumetric ( rice. 5 ). The combination of electron microscopy with other methods, for example, with autoradiography, histochemical, immunological research methods, makes it possible to conduct electron radioautography, electron histochemical, and 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 research objects, in particular chemical or physical fixation of tissues and microorganisms. After fixation, biopsy material and sectional material are dehydrated, poured into epoxy resins, cut with glass or diamond knives on special ultratomes, which make it possible to obtain ultrathin sections of tissue with a thickness of 30-50 nm. They are contrasted and then examined under an electron microscope. In a scanning (rastering) electron microscope, the surface of various objects is studied by depositing electron-dense substances on them in a vacuum chamber, and they examine the so-called. replicas that follow the contours of the sample.

Rice. 5. Electron diffraction pattern of a leukocyte and the bacteria it phagocytoses, 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 cannot be stained 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 thin thickness.

Ultraviolet and infrared microscopes designed for studying objects in the ultraviolet or infrared portion of the light spectrum. They are equipped with a fluorescent screen on which an image of the test drug 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, so in an ultraviolet microscope it is possible to obtain higher resolution than in a light microscope, where illumination is carried out by visible light radiation with a wavelength of 700--400 nm. Another advantage of this microscope is that objects invisible in a conventional light microscope become visible because 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 specimen 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.

Fluorescence microscope(ML-2, ML-3) is intended for studying luminescent objects, which is achieved by illuminating the latter using 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 sample under study, 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-ray radiation Therefore, such microscopes are equipped with a microfocus X-ray radiation source, an X-ray to visible image 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 microns, which makes it possible to study the fine structures of living matter.

Electron microscope designed for studying ultrafine structures that are indistinguishable in light microscopes. Unlike a light microscope, resolution in an electron microscope is determined not only by diffraction phenomena, but also by various aberrations of electronic lenses, which are almost impossible to correct. The microscope is aimed mainly by aperture through the use of small apertures of electron beams.

2.1 Historical background

The ability of a system of two lenses to produce enlarged images of objects was known already in the 16th century. in the Netherlands and Northern Italy to craftsmen who made spectacle glasses. There is information that around 1590 an M type device was built by Z. Jansen (Netherlands). The rapid spread of telescopes and their improvement, mainly by artisan opticians, began in 1609-10, when G. Galileo, studying the telescope he designed (see Telescope), used it as a telescope, changing the distance between the lens and an eyepiece. The first brilliant successes in the use of magnetism in scientific research are associated with the names of R. Hooke (around 1665; in particular, he established that animals and plant tissue 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. Mathematics appeared in Russia: here L. Euler (1762; Dioptrics, 1770–71) developed methods for calculating the optical components of microscopes. In 1827, J. B. Amici was the first to use an immersion lens in microscopy. In 1850, the English optician G. Sorby created the first microscope for observing objects in polarized light.

The widespread development of microscopic research methods and the improvement of various types of microscopy in the 2nd half of the 19th and 20th centuries. contributed significantly to the scientific activity of E. Abbe, who developed (1872-73) the now classical theory of the formation of images of non-self-luminous objects in Moscow. The English scientist J. Sirks laid the foundation for interference microscopy in 1893. In 1903, Austrian researchers R. Zsigmondy 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 magnetism. A great contribution to the theory and practice of microscopy was made by Sov. scientists - L. I. Mandelstam, D. S. Rozhdestvensky, A. A. Lebedev, V. P. Linnik.

2.2 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 stage 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 specimen, lens, and eyepiece) are also mandatory accessories. All these units 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 using the phase or interference contrast method are very different two- or three-lens systems. 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 lenses and mirrors are dark-field condensers. A separate group consists of epicondensers - necessary when observing using the dark field method in reflected light, a system of ring-shaped lenses and mirrors installed around the lens. UV microscopy uses special mirror-lens and lens condensers that are transparent to ultraviolet rays.

The lenses in most modern lenses are interchangeable and are selected depending on specific observation conditions. Often several lenses are mounted in one rotating (so-called revolver) head; Changing the lens in this case is carried out by simply turning the head. Based on the degree of correction of chromatic aberration (see Chromatic aberration), microlenses are distinguished between Achromats and apochromats (see Achromat). The first ones are the simplest in design; chromatic aberration in them is corrected for only two wavelengths, and the image remains slightly colored when illuminated by white light. Apochromats correct this aberration for three wavelengths and produce colorless images. The image plane of achromats and apochromats is somewhat curved (see Field curvature). Accommodation of the eye and the ability to view the entire field of view with the help of refocusing M. partly compensate for this disadvantage during visual observation, but it has a strong effect on microphotography - the extreme areas of the image are blurred. Therefore, microlenses with additional field curvature correction—planchromats and planapochromats—are widely used. In combination with conventional lenses, special projection systems are used - gomals, which are inserted instead of eyepieces and correct the curvature of the image surface (they are not suitable for visual observation).

In addition, microlenses differ: a) in spectral characteristics - into lenses for the visible region of the spectrum and for UV and IR microscopy (lens or mirror-lens); b) according to the length of the tube for which they are designed (depending on the design of the lens) - for lenses for a 160 mm tube, for a 190 mm tube and for the so-called. “tube lengths are infinity” (the latter create an image “at infinity” and are used in conjunction with an additional - so-called tube - lens, which transfers the image to the focal plane of the eyepiece); c) according to the medium between the lens and the preparation - dry and immersion; d) according to the observation method - into conventional, phase-contrast, interference, etc.; e) by type of preparation - for preparations with and without a cover glass. A separate type is epilenses (a combination of a conventional lens with an epicondenser). The variety of lenses is due to the variety of microscopic observation methods and microscopic designs, as well as differences in the requirements for correcting aberrations under different operating conditions. Therefore, each lens can only be used in the conditions for which it is designed. For example, a lens designed for a 160 mm tube cannot be used in a lens with a tube length of 190 mm; With a lens for preparations with a cover glass, preparations without a cover glass cannot be observed. It is especially important to comply with 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 cover slips when working with these objectives should be 0.17 mm. An immersion lens can only be used with the immersion for which it is designed.

Type of eyepiece used this method observation is determined by the choice of objective M. With achromats of low and medium magnification, Huygens eyepieces are used, with apochromats and achromats of high magnification - the so-called. compensation eyepieces designed so that their residual chromatic aberration is of a different sign than that of the 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 (the gomals mentioned above can also be included here). A separate group consists of quartz eyepieces, transparent to UV rays.

Various accessories to M. make it possible to improve observation conditions and expand research opportunities. Various types of illuminators 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 installations are used for microphotography; Drawing machines make it possible to sketch images. For quantitative studies, special devices are used (for example, microspectrophotometric attachments).

2.3 Types of microscopes

The design of a microscope, its equipment, and the characteristics of its main components are determined either by the scope of application, the range of problems, and the nature of the objects for which it is intended to study, or by the observation method(s) for which it is designed, or by both together. All this led to the creation of various types of specialized microscopy, making 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 microscopes, with the help of which one can observe various objects using 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—for observing transparent objects in chemistry, physics, etc. There are many models of biological M., differing in design and additional accessories that significantly expand the range of objects being studied. These accessories include: replaceable transmitted and reflected light illuminators; replaceable capacitors for working using light and dark field methods; phase contrast devices; eyepiece micrometers; microphoto attachments; sets of light filters and polarization devices that allow the use of fluorescent and polarization microscopy techniques in ordinary (non-specialized) microscopy. In auxiliary equipment for biological M., a particularly important role is played by microscopic equipment (see Microscopic equipment), intended for preparing preparations and performing various operations with them, including directly during observation (see Micromanipulator, Microtome).

Biological research cameras are equipped with a set of interchangeable lenses for various conditions and observation methods and types of preparations, including epi-lenses for reflected light and often phase-contrast objectives. The set of lenses corresponds to a set of eyepieces for visual observation and microphotography. Typically, such M. have binocular tubes for observation with both eyes.

Besides M. general purpose, in biology, various microscopes specialized in observation methods are also widely used (see below).

Inverted lenses are distinguished by the fact that the lens in them is located under the observed object, and the condenser is located on top. The direction of rays passing from top to bottom through the lens is changed by a system of mirrors, and they enter the observer’s eye, as usual, from bottom to top ( rice. 8). M. of this type are intended for the study of bulky objects that are difficult or impossible to place on the object tables of ordinary M. In biology, with the help of such M., they study those located in nutrient medium Tissue cultures that are placed in a thermostatic chamber to maintain a given temperature. Inverted M. are also used for research chemical reactions, determining the melting points of materials and in other cases when bulky auxiliary equipment is required to implement the observed processes. For microphotography and microcine filming, inverted cameras are equipped with special devices and cameras.

The inverted microscope design is especially convenient for observing structures in reflected light. various surfaces. Therefore, it is used in most metallographic M. In them, a sample (a section of a metal, alloy or mineral) is installed on a table with the polished surface down, and the rest of it can have free form 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 relative position of the nodes in such materials is the same as in ordinary (non-inverted) materials. The surface under study is often pre-etched, due to which the grains of its structure become sharply distinguishable from each other. In this type of microscopy, one 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 also 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 lamps are equipped with a set of replaceable light filters, by selecting which it is possible to select in the emission of the illuminator a part of the spectrum that excites the luminescence of a particular object under study. A filter is also selected that transmits only luminescent 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 light sources in fluorescent lamps are ultra-high-pressure mercury lamps, which produce 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 a mercury lamp illuminator, a set of light filters, etc. opaque illuminator for illuminating preparations from above.

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

Polarization microscopy is designed to study (with the help of optical compensators) changes in the polarization of light transmitted through an object or reflected from it, which opens up the possibility of quantitative or semi-quantitative determination of various characteristics of optically active objects. The components of such lenses are usually made in such a way as to facilitate precise measurements: the eyepieces are equipped with a crosshair, micrometer scale, or grid; rotating object table - with a goniometric dial for measuring the angle of rotation; Often a Fedorov table is attached to the object stage (see Fedorov table), which makes it possible to arbitrarily rotate and tilt the specimen to find the crystallographic and crystal optical axes. Polarized lenses are specially selected so that there are no internal stresses in their lenses that lead to depolarization of light. This type of lens usually has an auxiliary lens that can be switched on and off (the so-called Bertrand lens), used for observations in transmitted light; it allows one to consider interference figures (see Crystal optics) formed by light in the rear focal plane of the lens after passing through the crystal under study.

With the help of interference lenses, transparent objects are observed using the interference contrast method; many of them are structurally similar to conventional microscopes, differing only in the presence of a special condenser, lens, and measuring unit. If observations are made in polarized light, then such microscopes are equipped with a polarizer and analyzer. In terms of their field of application (mainly biological research), these micrometers can be classified as specialized biological micrometers. Microinterferometers are also often classified as interference micrometers—a special type of micrometer used to study the microrelief of the surfaces of machined metal parts.

Stereomicroscopes. Binocular tubes used in conventional microscopy, despite the convenience of observing with both eyes, do not provide a stereoscopic effect: in this case, the same rays enter both eyes at the same angles, only being divided into two beams by a prism system. Stereo microscopes, which provide truly three-dimensional perception of a micro-object, are actually two microscopes made as a single structure so that the right and left eyes observe the object from different angles ( rice. 10). Such microscopes are most widely used where it is necessary to perform any operations with an object during observation (biological research, surgery on blood vessels, the brain, the eye - microsurgery, assembly of miniature devices, for example transistors), - stereoscopic perception facilitates these operations. The convenience of orientation in the microscope's field of view is also facilitated by the inclusion in its optical design of prisms that play the role of turning systems (see Turning system); the image in such M. is upright, not inverted. So what is the usual angle between the optical axes of objectives in stereo microscopes? 12°, their numerical aperture, as a rule, does not exceed 0.12. Therefore, the useful increase in such M. is no more than 120.

Comparison lenses consist of two structurally combined conventional 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 microscope, which allows them to be directly compared by color, structure and distribution of elements and other characteristics. Comparison tests are widely used in assessing the quality of surface treatment, determining grades (comparison with a reference sample), etc. Special tests of this type are used in criminology, in particular for identifying the weapon from which the bullet under test was fired.

In television M., operating according to a microprojection scheme, the image of the drug 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 microscopes, it is possible, purely electronically, by changing the parameters of the electrical circuit through which the signals pass, to change the contrast of the image and adjust its brightness. Electrical amplification of signals allows images to be projected onto a large screen, while conventional microprojection requires extremely strong lighting, often harmful to microscopic objects. The great advantage of television cameras is that they can be used to remotely study objects whose proximity is dangerous for an observer (for example, radioactive objects).

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 the alloy, and perform other similar measurements. The conversion of television images into a series of electrical signals (pulses) made it possible to construct automatic counters of microparticles that register them by the number of pulses.

The purpose of measuring instruments is to accurately measure the linear and angular dimensions of objects (often quite large ones). Based on the method of measurement, they can be divided into two types. Measuring micrometers 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 micrometer. In such micrometers, it is not the object itself that is measured directly (using a scale or a screw ocular micrometer (see Ocular micrometer)) its image in the focal plane of the eyepiece, and only then, based on the known value of the lens magnification, the measured distance on the object is calculated. Often in these microscopes, images of objects are compared with standard profiles printed on the plates of interchangeable eyepiece heads. In measuring M. Type 2: the stage with the object and the M body can be moved relative to each other using precise mechanisms (more often, the table is relative to the body); By measuring this movement with a micrometer screw or scale rigidly attached to the object stage, the distance between the observed elements of the object is determined. There are measuring meters in which measurements are made only in one direction (single-axis meters). M. with movements of the object table in two perpendicular directions (limits of movement up to 200×500 mm) are much more common; For special purposes, microscopes are used in which measurements (and, consequently, relative movements of the table and the microscope body) 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 purpose, the object stage is made rotating and equipped with a scale and a vernier for measuring rotation angles. The most accurate measuring microscopes of the 2nd 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 type 2 meters is significantly higher than in type 1 meters. The best models have accuracy linear measurements usually on the order of 0.001 mm, the accuracy of measuring angles is on 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 particularly precise measurements (for example, geodetic, astronomical, etc.), readings on linear scales and divided circles of goniometer instruments are made using special reading micrometers—scale micrometers and micrometers. The former have an auxiliary glass scale. By adjusting the magnification of the 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 is even higher (about 0.0001 mm) in micrometers, in the eyepiece 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 a whole number of turns (or half turns) of the micrometer screw.

In addition to those described above, there are a significant number of even more highly specialized types of meters, for example, machines for counting and analyzing traces elementary particles and nuclear fission fragments in nuclear photographic emulsions (see Nuclear photographic emulsion), high-temperature microscopes for studying objects heated to a temperature of about 2000 °C, contact microscopes for studying the surfaces of living organs of animals and humans (the lens in them is pressed close to the object being studied surfaces, and focusing of M. is carried out by a special built-in system).

Conclusion

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

Over time, we can expect to attract 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 microscopes 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 units connected to 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 time resolution of microscope detectors (screens), as well as the use of powerful modern computers.

List of used literature

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

2. First health care. - M.: Great Russian Encyclopedia. 1994

3. encyclopedic Dictionary 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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Today it's hard to imagine scientific activity a person 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 when making an accurate diagnosis and monitoring the progress of treatment. Using a microscope, new drugs are developed and introduced, and 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 capable of distinguishing details of an object that are separated from each other by at least 0.08 mm. Using a light microscope, you can see parts with a distance of up to 0.2 microns. An electron microscope allows you to obtain a resolution of up to 0.1-0.01 nm.

The invention of the microscope, a device so important for all science, was primarily due to the influence of the development of optics. Some optical properties of curved surfaces were known to Euclid (300 BC) and Ptolemy (127-151), but their magnifying ability was not found practical application. In this regard, the first glasses were invented by Salvinio degli 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 Zacharius Jansen (Z. Jansen). The invention involved Zacharius Jansen mounting two convex lenses inside a single tube, thereby laying the foundation for the creation of complex microscopes. Focusing on the object under study was achieved through a retractable tube. The microscope magnification ranged from 3 to 10 times. And it was a real breakthrough in the field of microscopy! He significantly improved each of his next microscopes.

During this period (XVI century), Danish, English and Italian research instruments gradually began their development, laying the foundation of 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 lens and the eyepiece.

Later, in 1624, having achieved the production of shorter focal length 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 the microscope in scientific biological research were achieved by R. Hooke, who was the first to describe a plant cell (around 1665). In his book Micrographia, Hooke described the structure of a microscope.

In 1681, the Royal Society of London discussed this peculiar situation in detail at its meeting. 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 spermatozoa of various protozoa, structural details bone tissue (1673-1677).

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

Leeuwenhoek's best magnifying glasses were magnified 270 times. With them, he saw for the first time blood cells, the movement of blood in the capillary vessels of the tadpole's tail, and the striping of muscles. He discovered ciliates. He plunged for the first time into the world of microscopic single-celled 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 ingests 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. Diviney, by attaching a field lens to the eyepiece, created a modern type eyepiece. In 1673, Havelius introduced a micrometer screw, and Hertel proposed placing a mirror under the microscope table. Thus, the microscope began to be mounted from those basic parts that are part of a modern biological microscope.

In the middle of the 17th century Newton discovered a complex composition white light and spread it out with a prism. Roemer proved that light travels at a finite speed and measured it. Newton expressed 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, striking the retina with impacts, produce the physiological sensation of light . Huygens first spoke about the wave-like nature of light and proved how naturally it explains both the laws of simple reflection and refraction, and the laws of double refraction in Iceland spar. The thoughts of Huygens and Newton met in sharp contrast. Thus, in the 17th century. in a heated 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 question was resolved only after more than a hundred years by Fresnel, a talented researcher such as science knew.

How does a stream of propagating waves - Huygens's idea - differ from a stream of rushing small particles - Newton's idea? Two signs:

1. Having met, the waves can be mutually destroyed if the hump of one falls on the valley of the other. Light + light put together can create darkness. This phenomenon interference, these are Newton's rings, not understood by Newton himself; This cannot happen with particle flows. Two streams of particles are always a double stream, double light.

2. The flow of particles passes straight through the hole, without diverging to the sides, and the flow of waves certainly diverges and 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 insignificant diffraction, and from its magnitude he determined the wavelength of light. From the interference phenomena that are so well known to opticians who polish to "one color", to "two stripes", he also measured the wavelength - this is half a micron (half a thousandth of a millimeter). And from here the wave theory and the exceptional subtlety and sharpness of penetration into the essence of living matter became undeniable. Since then, we have all confirmed and applied Fresnel’s thoughts in various modifications. But even without knowing these thoughts, you can improve the microscope.

That's how it was in XVIII century, although events developed very slowly. Now it is difficult to even imagine that Galileo’s first telescope, 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 represents glass, in which one of the main parts is heavy lead oxide, which has a disproportionately large dispersion.

In 1824, the enormous success of the microscope was achieved by Sallig's simple practical idea, reproduced by the French company Chevalier. The lens, which previously consisted of a single lens, was 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 - 500 and even 1000 times. The limit of ultimate vision has moved from two to one micron. Leeuwenhoek's microscope was left far behind.

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

The following was achieved:

Firstly, the maximum resolution has moved from half a micron to one tenth of a micron.

Secondly, in the construction of the microscope, instead of crude empiricism, a high level of science was introduced.

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

A headquarters of scientists, opticians and computer scientists working at the Zeiss company was formed. In major works, Abbe's students gave the theory of the microscope and optical instruments in general. A system of measurements has been developed to determine the quality of the microscope.

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

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

An optical physicist senses when an object with a thickness of a thousandth, ten-thousandth, or in some cases even one hundred-thousandth of a wavelength is inserted into the path of a light wave. The wavelength itself has been measured by physicists with an accuracy of one ten-millionth of its magnitude. Is it possible to think that opticians who have joined forces with cytologists will not master that hundredth of a wavelength, which is the task they set? There are dozens of ways to get around the limit set by wavelength. You know one of these bypasses, the so-called ultramicroscopy method. If microbes invisible under a microscope are spaced far apart, you can shine a bright light on them from the side. No matter how small they are, they will sparkle like a star against a dark background. Their form cannot be determined, one can only state 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 scattering objects in microscopes. In the middle of the 20th century. The electron microscope was invented, and in 1953 the Finnish physiologist A. Wilska invented the anoptral microscope.

M.V. made a great contribution to the development of problems of theoretical and applied optics, improvement of microscope optical systems and microscopic equipment. 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 issue of imaging transparent objects in a microscope. - Tr. GOI, 1940, vol. 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.

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

Opening cellular structure occurred at a time of human development when experimental physics began to claim to be called the mistress of all sciences. A society of the greatest scientists was created in London, who focused on specific physical laws in improving the world. There were no political debates at the meetings of community members; 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 Invisibles.” The first who stood at the origins of the creation of the society was Robert Boyle, Hooke's great mentor. The Collegium published the necessary scientific literature. The author of one of the books was Robert Hooke who was also part of this secret scientific community. Even in those years, Hooke 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 magnify the objects being examined by 3-10 times. Robert Hooke improved this product, which played a role main role in the upcoming opening.

Robert Hooke spent a long time observing various small specimens through the microscope he created, and one day he took an ordinary stopper from a vessel to view it. Having examined a thin section of this cork, the scientist was surprised by the complexity of the structure of the substance. An interesting pattern of many cells appeared to his gaze, surprisingly similar to a honeycomb. Since cork is a plant product, Hooke began to study sections of plant stems using a microscope. A similar picture was repeated everywhere - a set of honeycombs. Through the microscope, many rows of cells were visible, 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 functions. This science is used in many areas, including medicine and industry.

With name M. Malpighi This outstanding biologist and physician was associated with an important period of microscopic research into 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,
  • capillary vessels,
  • skin,
  • liver,
  • spleen,
  • plant tissues.

In the study of these objects he achieved such perfection that he became
one of the creators of microscopic anatomy. Malpighi was the first to use
microscope for studying blood circulation.

Using 180x magnification, Malpighi made a discovery in the theory of blood circulation: looking at a frog lung specimen under a microscope, he noticed air bubbles surrounded by a film and small blood vessels, saw an extensive network of capillary vessels connecting arteries with 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 the development of the embryo in a chicken egg, as well as anatomical structure plants indicate very careful observations.

Nehemiah Grew(1641 – 1712). English botanist and physician, microscopist,

founder of plant anatomy. The main works are devoted to the structure and sex of plants. Along with M. Malpighi, he 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” and introduced the concepts of “tissue” and “parenchyma” into botany. Studying the structure of flowers, I came to the conclusion that they are fertilization organs in plants.

Leeuwenhoek Anthony(24.10.1632–26.08.1723), Dutch naturalist. He worked in a textile shop in Amsterdam. Back in Delft, free time I was grinding lenses. In total, Leeuwenhoek made about 250 lenses during his life, achieving 300-fold magnification and achieving great perfection in this. The lenses he made, which he inserted into metal holders with a needle attached to them to attach the object of observation, gave 150-300x magnification. With the help of such “microscopes” Leeuwenhoek first observed and sketched:

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

First described parthenogenesis in aphids (1695–1700).

Leeuwenhoek took the position of preformationism, arguing that the formed embryo is already contained in the “animalcule” (sperm). 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. By monitoring the movement of blood through the capillaries, he showed that capillaries connect arteries and veins. For the first time he observed red blood cells and discovered that in birds, fish and frogs they are oval, and 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 the achromatic microscope in scientific research has served as a new impetus for the development of histology. IN early XIX V. The first image of plant cell nuclei was made. J. Purkinje(in 1825-1827) described the nucleus in a chicken egg, 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 core is a mandatory part plant cell. Thus, material gradually began to accumulate about the microscopic organization of animals and plants and the structure of “cells” (cellula), first seen by R. Hooke.

Creation cell theory had a huge progressive influence on the development of biology and medicine. IN mid-19th V. a period of rapid development of descriptive histology began. On the basis of cellular theory, the composition of various organs and tissues and their development were studied, which made it possible even then to create the basic outlines of microscopic anatomy and to clarify the classification of tissues taking into account their microscopic structure (A. Kölliker and others).