Cytology is the science of the structure and function of cells. Cell biology cytology scientists

Cytology is a science that studies cellular interactions and cell structure, which, in turn, is a fundamental component of any living organism. The term itself comes from the ancient Greek concepts “kitos” and “logos”, meaning, respectively, cell and teaching.

Emergence and early development Sciences

Cytology is one of a whole galaxy of sciences that spun off from biology in modern times. The forerunner of its occurrence was the invention of the microscope in the 17th century. It was by observing life through such a primitive construction that the Englishman first discovered that everything is made of cells. Thus, he laid the foundation for what cytology studies today. Ten years later, another scientist, Anthony Leeuwenhoek, discovered that cells have a strictly ordered structure and patterns of functioning. He also discovered the existence of nuclei. At the same time for a long time the understanding of the cell and its functioning was hampered by the unsatisfactory quality of microscopes of that time. Next important steps were made in the middle of the 19th century. Then the technology was significantly improved, which made it possible to create new concepts, to which cytology owes its intensive development. This is, first of all, the discovery of protoplasm and the emergence

Based on the empirical knowledge accumulated by that time, biologists M. Schleiden and T. Schwann almost simultaneously proposed to the scientific world the idea that all animal and plant cells are similar to each other, and that each such cell itself has all the properties and functions of a living organism . This understanding of the complex life forms on the planet had a significant impact on the path that cytology followed. This also applies to its modern development.

Discovery of protoplasm

The next important achievement in the mentioned field of knowledge was the discovery and description of the properties of protoplasm. It is a substance that fills cellular organisms and also provides a medium for cell organs. Later, scientists' knowledge about this substance evolved. Today it is called cytoplasm.

Further development and discovery of genetic inheritance

In the second half of the 19th century, discrete bodies were discovered that were contained in them. They were called chromosomes. Their study revealed to humanity the laws of genetic continuity. Major contribution The Austrian Gregor Mendel entered this area at the end of the 19th century.

Current state of science

For the modern scientific community, cytology is one of the most important branches of biological knowledge. What made it so was the development of scientific methodology and technical capabilities. The methods of modern cytology are widely used in research useful to people, for example, in the study of cancer, growing artificial organs, as well as in selection, genetics, breeding new species of animals and plants, and so on.

One of the new extremely promising disciplines is cytology, the science of cells. Modern cytology is a complex science. It has the closest connections with other biological sciences, for example, with botany, zoology, physiology, the study of the evolution of the organic world, as well as with molecular biology, chemistry, physics, and mathematics. Cytology is one of the relatively young biological sciences, its age is about 100 years, although the very concept of a cell was introduced into use by scientists much earlier.

A powerful stimulus to the development of cytology was the development and improvement of installations, instruments and instruments for research. Electron microscopy and the capabilities of modern computers along with chemical methods give everything last years new materials for research.

Cytology as a science, its formation and tasks

Cytology (from the Greek κύτος - bubble-like formation and λόγος - word, science) is a branch of biology, the science of cells, the structural units of all living organisms, which sets itself the task of studying the structure, properties, and functioning of a living cell.

The study of the smallest structures of living organisms became possible only after the invention of the microscope - in the 17th century. The term “cell” was first proposed in 1665 by the English naturalist Robert Hooke (1635–1703) to describe the cellular structure of a cork section observed under a microscope. Examining thin sections of dried cork, he discovered that they “consisted of many boxes.” Hooke called each of these boxes a cell (“chamber”).” In 1674, the Dutch scientist Antonie van Leeuwenhoek discovered that the substance inside the cell is organized in a certain way.

However, the rapid development of cytology began only in the second half of the 19th century. as microscopes develop and improve. In 1831, R. Brown established the existence of a nucleus in a cell, but failed to appreciate the full importance of his discovery. Soon after Brown's discovery, several scientists became convinced that the nucleus was immersed in the semi-liquid protoplasm filling the cell. Initially, the basic unit of biological structure was considered to be fiber. However, already at the beginning of the 19th century. Almost everyone began to recognize a structure called a vesicle, globule or cell as an indispensable element of plant and animal tissues. In 1838–1839 German scientists M. Schleiden (1804–1881) and T. Schwann (1810–1882) almost simultaneously put forward the idea of ​​cellular structure. The statement that all tissues of animals and plants are composed of cells constitutes the essence cell theory. Schwann coined the term "cell theory" and introduced this theory to the scientific community.

According to the cellular theory, all plants and animals consist of similar units - cells, each of which has all the properties of a living thing. This theory has become the cornerstone of all modern biological thinking. At the end of the 19th century. The main attention of cytologists was directed to a detailed study of the structure of cells, the process of their division and elucidation of their role. At first, when studying the details of cell structure, one had to rely mainly on visual examination of dead rather than living material. Methods were needed that would make it possible to preserve protoplasm without damaging it, to make sufficiently thin sections of tissue that passed through the cellular components, and also to stain sections to reveal details of the cellular structure. Such methods were created and improved throughout the second half of the 19th century.

The concept was of fundamental importance for the further development of cell theory genetic continuity of cells. First, botanists and then zoologists (after the contradictions in the data obtained from the study of certain pathological processes were clarified) recognized that cells arise only as a result of the division of already existing cells. In 1858, R. Virchow formulated the law of genetic continuity in the aphorism “Omnis cellula e cellula” (“Each cell is a cell”). When the role of the nucleus in cell division was established, W. Flemming (1882) paraphrased this aphorism, proclaiming: “Omnis nucleus e nucleo” (“Each nucleus is from the nucleus”). One of the first important discoveries in the study of the nucleus was the discovery of intensely colored filaments in it, called chromatin. Subsequent studies showed that during cell division these filaments are assembled into discrete bodies - chromosomes, that the number of chromosomes is constant for each species, and in the process of cell division, or mitosis, each chromosome is split into two, so that each cell receives the number of chromosomes typical for that species.

Thus, even before the end of the 19th century. two important conclusions were reached. One was that heredity is the result of the genetic continuity of cells provided by cell division. Another thing is that there is a mechanism for the transmission of hereditary characteristics, which is located in the nucleus, or more precisely, in the chromosomes. It was found that, thanks to the strict longitudinal segregation of chromosomes, daughter cells receive exactly the same (both qualitatively and quantitatively) genetic constitution as the original cell from which they originated.

The second stage in the development of cytology begins in the 1900s, when the laws of heredity, discovered by the Austrian scientist G.I. Mendel back in the 19th century. At this time, a separate discipline emerged from cytology - genetics, the science of heredity and variability, studying the mechanisms of inheritance and genes as carriers of hereditary information contained in cells. The basis of genetics was chromosomal theory of heredity– the theory according to which chromosomes contained in the cell nucleus are carriers of genes and represent the material basis of heredity, i.e. the continuity of the properties of organisms in a number of generations is determined by the continuity of their chromosomes.

New techniques, especially electron microscopy, the use of radioactive isotopes and high-speed centrifugation, which emerged after the 1940s, allowed even greater advances in the study of cell structure. At the moment, cytological methods are actively used in plant breeding and in medicine - for example, in the study of malignant tumors and hereditary diseases.

Basic principles of cell theory

In 1838-1839 Theodor Schwann and the German botanist Matthias Schleiden formulated the basic principles of cell theory:

1. The cell is a unit of structure. All living things consist of cells and their derivatives. The cells of all organisms are homologous.

2. The cell is a unit of function. The functions of the whole organism are distributed among its cells. The total activity of an organism is the sum of the vital activity of individual cells.

3. The cell is a unit of growth and development. The growth and development of all organisms is based on the formation of cells.

The Schwann–Schleiden cell theory belongs to the greatest scientific discoveries of the 19th century. At the same time, Schwann and Schleiden considered the cell only as a necessary element of the tissues of multicellular organisms. The question of the origin of cells remained unresolved (Schwann and Schleiden believed that new cells are formed by spontaneous generation from living matter). Only the German physician Rudolf Virchow (1858-1859) proved that every cell comes from a cell. At the end of the 19th century. ideas about the cellular level of organization of life are finally formed. The German biologist Hans Driesch (1891) proved that a cell is not an elementary organism, but an elementary biological system. Gradually, a special science of cells is being formed - cytology.

Further development of cytology in the 20th century. is closely related to the development of modern methods for studying cells: electron microscopy, biochemical and biophysical methods, biotechnological methods, computer technology and other areas of natural science. Modern cytology studies the structure and functioning of cells, metabolism in cells, the relationship of cells with the external environment, the origin of cells in phylogenesis and ontogenesis, patterns of cell differentiation.
Currently, the following definition of a cell is accepted. A cell is an elementary biological system that has all the properties and signs of life. The cell is the unit of structure, function and development of organisms.

Unity and diversity of cell types

There are two main morphological types of cells that differ in the organization of the genetic apparatus: eukaryotic and prokaryotic. In turn, according to the method of nutrition, two main subtypes of eukaryotic cells are distinguished: animal (heterotrophic) and plant (autotrophic). A eukaryotic cell consists of three main structural components: nucleus, plasmalemma and cytoplasm. A eukaryotic cell differs from other types of cells primarily by the presence of a nucleus. The nucleus is the place of storage, reproduction and initial implementation of hereditary information. The nucleus consists of the nuclear envelope, chromatin, nucleolus and nuclear matrix.

Plasmalemma (plasma membrane) is a biological membrane that covers the entire cell and delimits its living contents from the external environment. A variety of cell membranes (cell walls) are often located on top of the plasmalemma. In animal cells, cell walls are usually absent. Cytoplasm is a part of a living cell (protoplast) without a plasma membrane and nucleus. The cytoplasm is spatially divided into functional zones (compartments) in which various processes occur. The composition of the cytoplasm includes: the cytoplasmic matrix, cytoskeleton, organelles and inclusions (sometimes inclusions and the contents of vacuoles are not considered to be the living substance of the cytoplasm). All cell organelles are divided into non-membrane, single-membrane and double-membrane. Instead of the term “organelles,” the outdated term “organelles” is often used.

Non-membrane organelles of a eukaryotic cell include organelles that do not have their own closed membrane, namely: ribosomes and organelles built on the basis of tubulin microtubules - the cell center (centrioles) and movement organelles (flagella and cilia). In the cells of most unicellular organisms and the vast majority of higher (land) plants, centrioles are absent.

Single-membrane organelles include: endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, spherosomes, vacuoles and some others. All single-membrane organelles are interconnected into a single vacuolar system of the cell. True lysosomes are not found in plant cells. At the same time, animal cells lack true vacuoles.

Double-membrane organelles include mitochondria and plastids. These organelles are semi-autonomous because they have their own DNA and their own protein-synthesizing apparatus. Mitochondria are found in almost all eukaryotic cells. Plastids are found only in plant cells.
A prokaryotic cell does not have a formed nucleus - its functions are performed by a nucleoid, which includes a ring chromosome. In a prokaryotic cell there are no centrioles, as well as single-membrane and double-membrane organelles - their functions are performed by mesosomes (invaginations of the plasmalemma). Ribosomes, organelles of movement and membranes of prokaryotic cells have a specific structure.

The history of cytology is closely connected with the invention, use and improvement of the microscope. This is because the human eye is unable to distinguish objects smaller than 0.1 mm, which is 100 micrometers (abbreviated micron or µm). The sizes of cells (and even more so, intracellular structures) are significantly smaller. For example, the diameter of an animal cell usually does not exceed 20 microns, a plant cell - 50 microns, and the length of the chloroplast of a flowering plant - no more than 10 microns. Using a light microscope, you can distinguish objects with a diameter of tenths of a micron. Therefore, light microscopy is the main, specific method for studying cells.

Note. 1 millimeter (mm) = 1,000 micrometers (µm) = 1,000,000 nanometers (nm). 1 nanometer = 10 angstroms (Å). One angstrom is approximately the diameter of a hydrogen atom.

The first optical instruments (simple lenses, glasses, magnifying glasses) were created back in the 12th century. But complex optical tubes, consisting of two or more lenses, appeared only at the end of the 16th century. Galileo Galilei, father and son Jansens, physicist Druebel and other scientists took part in the invention of the light microscope. The first microscopes were used to study a wide variety of objects.

· 1665: R. Hooke, observing for the first time under a microscope a thin section of balsa wood, discovered empty cells, which he called celluli , or cells; in fact, R. Hooke observed only the membranes of plant cells; Subsequently, R. Hooke studied sections of living stems and discovered similar cells in them, which, unlike dead cork cells, were filled with “nutritional juice.” R. Hooke outlined his observations in his work “Micrography, or some physiological descriptions of the smallest bodies using magnifying glasses” (1665);

· 1671: Marcello Malpighi (Italy) and Nehemiah Grew (England), studying the anatomical structure of plants, came to the conclusion that all plant tissues consist of vesicle cells. The term “fabric” (“lace”) was first used by N. Grew. In the works of R. Hooke, M. Malpighi and N. Grew, the cell is considered as an element, as an integral part of the tissue. Cells are separated from each other by common partitions and therefore cannot be thought of outside the tissue, outside the body;

· 1674: Dutch amateur microscopist Antonio van Leeuwenhoek (1680) observed single-celled organisms - “animalcules” (ciliates, sarcoids, bacteria) and other forms of single cells (blood cells, spermatozoa);

During this period, the main part of the cell was considered to be its wall, and only two hundred years later it became clear that the main thing in the cell is not the wall, but the internal contents. In the 18th century Fundamental observations of protozoa were carried out by the German amateur naturalist Martin Ledermüller. However, during this period, new information about the cell accumulated slowly, and in the field of zoology more slowly than in botany, since the real cell walls, which served as the main subject of research, are characteristic only of plant cells. In relation to animal cells, scientists did not dare to apply this term and identify them with plant cells.

Subsequently, as the microscope and microscopy technology improved, information about animal and plant cells also accumulated. Gradually, ideas about the cell as an elementary organism were formed: later the German physiologist Ernst von Brücke (1861) called the cell an elementary organism. By the 30s of the 19th century, a lot of information had accumulated on cell morphology, and it was established that the cytoplasm and nucleus are its obligatory components.

· 1802, 1808: C. Brissot-Mirbe established the fact that all plant organisms are formed by tissues that consist of cells.

· 1809: J.B. Lamarck extended Brissot-Mirbet's idea of ​​cellular structure to animals.

· 1825: J. Purkinė discovered the nucleus in the eggs of birds.

· 1831: R. Brown first described the nucleus in plant cells.

· 1833: R. Brown came to the conclusion that the nucleus is an essential part of the plant cell.

· 1839: J. Purkinė discovered protoplasm(gr. protoss- first and plasma fashioned, shaped) - semi-liquid gelatinous contents of cells.

· 1839: T. Schwann summarized all the data accumulated by this time and formulated the cell theory.

· 1858: R. Virchow proved that all cells are formed from other cells by division.

· 1866: Haeckel established that the preservation and transmission of hereditary characteristics is carried out by the nucleus.

· 1866-1898: The main components of a cell that can be seen under an optical microscope are described. Cytology takes on the character of an experimental science.

· 1872: Professor of Dorpat (Tartus) University E. Russov,

· 1874: Russian botanist I.D. Chistyakov was the first to observe cell division.

· 1878: W. Fleming introduced the term “mitosis” and described the stages of cell division.

· 1884: V. Roux, O. Hertwig, E. Strassburger put forward the nuclear theory of heredity, according to which information about the hereditary characteristics of a cell is contained in the nucleus.

· 1888: E. Strasburger established the phenomenon of reduction in the number of chromosomes during meiosis.

· 1900: The advent of genetics was followed by the development of cytogenetics, which studies the behavior of chromosomes during division and fertilization.

· 1946: The use of the electron microscope began in biology, making it possible to study the ultrastructures of cells.

Cytology - the science that studies structure chemical composition and functions of cells, their reproduction, development and interaction in a multicellular organism.

Subject of cytology- cells of single- and multicellular prokaryotic and eukaryotic organisms.

Objectives of cytology:

1. Study of the structure and functions of cells and their components (membranes, organelles, inclusions, nucleus).

2. Study of the chemical composition of cells, biochemical reactions occurring in them.

3. Study of the relationships between cells of a multicellular organism.

4. Study of cell division.

5. Studying the possibility of cells adapting to changes environment.

To solve problems in cytology, various methods are used.

Microscopic methods: allow you to study the structure of the cell and its components using microscopes (light, phase-contrast, fluorescent, ultraviolet, electron); light microscopy is based on the flow of light; studies cells and their large structures; electron microscopy - the study of small structures (membranes, ribosomes, etc.) in a beam of electrons with a wavelength shorter than that of visible light. Phase contrast microscopy is a method of obtaining images in optical microscopes, in which the phase shift of an electromagnetic wave is transformed into intensity contrast. Phase contrast microscopy was invented by Fritz Zernike, for which he received the Nobel Prize in 1953. Designed for studying living, non-colored objects.

Cyto- And histochemical methods- based on the selective action of reagents and dyes on certain substances of the cytoplasm; used to establish the chemical composition and localization of various components (proteins, DNA, RNA, lipids, etc.) in cells.

Histological method is a method of preparing microspecimens from native and fixed tissues and organs. The native material is frozen, and the fixed object goes through the stages of compaction and embedding in paraffin. Sections are then prepared from the material being examined, stained, and embedded in Canada balsam.

Biochemical methods make it possible to study the chemical composition of cells and the biochemical reactions occurring in them.

Method of differential centrifugation (fractionation): based on different rates of sedimentation of cell components; first, the cells are destroyed to a uniform (homogeneous) mass, which is transferred into a test tube with a solution of sucrose or cesium chloride and subjected to centrifugation; isolates individual components of the cell (mitochondria, ribosomes, etc.) for subsequent study by other methods.

X-ray diffraction analysis method: after introducing metal atoms into the cell, the spatial configuration (spatial arrangement of atoms and groups of atoms) and some physical properties macromolecules (protein, DNA).

Autoradiography method- introduction of radioactive (labeled) isotopes into the cell - most often isotopes of hydrogen (3 H), carbon (14 C) and phosphorus (32 P); The molecules being studied are detected by radioactive labels using a radioactive particle counter or by their ability to expose photographic film, and then their inclusion in substances synthesized by the cell is studied; allows you to study the processes of matrix synthesis and cell division.

Time-lapse filming and photography method allows you to trace and record the processes of cell division through powerful light microscopes.

Microsurgical methods- surgical impact on the cell: removal or implantation of cell components (organelles, nucleus) from one cell to another in order to study their functions, microinjection of various substances, etc.

Cell culture method- growing individual cells of multicellular organisms on nutrient media under sterile conditions; makes it possible to study the division, differentiation and specialization of cells, to obtain clones of plant organisms.

Knowledge of the basics of chemical and structural organization, principles of functioning and mechanisms of cell development is extremely important for understanding the similar features inherent in complex organisms of plants, animals and humans. The development of the IVF method is an example of the practical application of cytological knowledge.

Great Medical Encyclopedia

Cytology is the science of the structure, functions and development of animal and plant cells, as well as single-celled organisms and bacteria.

Etymology of the term cytology: (Greek language) kytos - container, cell + logos teaching.

Cytological studies are essential for the diagnosis of human and animal diseases.

There are general and specific cytology.

General cytology(cell biology) studies the structures common to most types of cells, their functions, metabolism, responses to damage, pathological changes, reparative processes and adaptation to environmental conditions.

Private cytology explores the characteristics of individual cell types in connection with their specialization (in multicellular organisms) or evolutionary adaptation to the environment (in protists and bacteria).

The development of cytology is historically associated with the creation and improvement of the microscope and histological research methods. The term “cell” was first used by B. Hooke (1665), who described the cellular structure (more precisely, cellulose cell walls) of a number of plant tissues. In the 17th century, Hooke's observations were confirmed and developed by M. Malpighi and N. Grew, (1671), A. Leeuwenhoek. In 1781, F. Fontana published drawings of animal cells with nuclei.

In the first half of the 19th century, the idea of ​​the cell as one of the structural units of the body began to take shape. In 1831, R. Brown discovered a nucleus in plant cells, gave it the name “nucleus” and assumed the presence of this structure in all plant and animal cells. In 1832, V. S. Dumortier, and in 1835, H. Mohl, observed the division of plant cells. In 1838, M. Schleiden described the nucleolus in the nuclei of plant cells.

The prevalence of cellular structure in the animal kingdom was shown by the studies of R. J. N. Dutrochet (1824), F. V. Raspail (1827), and the schools of J. Purkinje and I. Müller. J. Purkinje was the first to describe the nucleus of an animal cell in 1825, developed methods for staining and clearing cell preparations, used the term “protoplasm”, and was one of the first who tried to compare the structural elements of animal and plant organisms (1837).

In 1838-1839 T. Schwann formulated the cell theory, in which the cell was considered as the basis of the structure, life activity and development of all animals and plants. T. Schwann's concept of the cell as the first stage of organization, possessing the entire complex of properties of living things, has retained its significance in the past.

The transformation of cell theory into a universal biological doctrine was facilitated by the discovery of the nature of protozoa. In 1841-1845. S. Th. Siebold formulated the concept of single-celled animals and extended the cell theory to them.

An important stage in the development of cytology was the creation by R. Virchow of the doctrine of cellular pathology. He viewed cells as the material substrate of diseases, which attracted not only anatomists and physiologists, but also pathologists to their study. R. Virchow also postulated the origin of new cells only from pre-existing ones. To a large extent, under the influence of the works of R. Virchow and his school, a revision of views on the nature of cells began. If previously the most important structural element of a cell was considered its shell, then in 1861 M. Schultze gave a new definition of a cell as “a lump of protoplasm, inside which lies the nucleus”; that is, the nucleus was finally recognized as an essential component of the cell. In the same 1861, E. W. Brucke showed the complexity of the structure of protoplasm.

The discovery of cell organelles - the cell center, mitochondria, Golgi complex, as well as the discovery of nucleic acids in cell nuclei contributed to the establishment of ideas about the cell as a complex multicomponent system. Study of mitosis processes [E. Strasburger (1875); P. I. Neremezhko (1878); V. Flemming (1878)] led to the discovery of chromosomes, the establishment of the rule of species constancy of their number (K. Rabl, 1885] and the creation of the theory of chromosome individuality (Th. Boveri, 1887). These discoveries, along with the study of the processes of fertilization, the biological essence of which he found out O. Hertwig (1875), phagocytosis, cell reactions to stimuli contributed to the fact that at the end of the 19th century, cytology became an independent branch of biology. J. B. Carnoy (1884) first introduced the concept of “cell biology” and formulated the idea of ​​cytology as a science. , which studies the form, structure, function and evolution of cells.

G. Mendel’s establishment of the laws of inheritance of characteristics and their subsequent interpretation, given at the beginning of the 20th century, had a great influence on the development of cytology. These discoveries led to the creation of the chromosomal theory of heredity and the formation of a new direction in cytology - cytogenetics, as well as karyology.

A major event in cell science was the development of the tissue culture method and its modifications - the method of single-layer cell cultures, the method of organ cultures of tissue fragments at the boundary of the nutrient medium and the gas phase, the method of culture of organs or their fragments on the membranes of chicken embryos, in animal tissues or in nutrient media. environment. They made it possible to observe the vital activity of cells outside the body for a long time, to study in detail their movement, division, differentiation, etc. The method of single-layer cell cultures, which played a large role in the development of not only cytology, but also virology, as well as receiving a number of antiviral vaccines. The intravital study of cells is greatly facilitated by microfilming, phase-contrast microscopy, fluorescent microscopy, microsurgery, and vital staining. These methods have made it possible to obtain much new information about the functional significance of a number of cellular components.

Introduction to Cytology quantitative methods research led to the establishment of the law of species constancy of cell sizes, later refined by E. M. Vermeule and known as the law of constancy of minimum cell sizes. W. Jacobi (1925) discovered the phenomenon of sequential doubling of the volume of cell nuclei, which in many cases corresponds to a doubling of the number of chromosomes in cells. Changes in nuclear size associated with functional state cells as in normal conditions, and in pathology (Ya. E. Hesip, 1967).

Raspail began to use methods of chemical analysis in cytology back in 1825. However, the works of L. Lison (1936), D. Glick (1949), and A. G. E. Perse (1953) were decisive for the development of cytochemistry. B.V. Kedrovsky (1942, 1951), A.L. Shabadash (1949), G.I. Roskin and L.B. Levinson (1957) also made great contributions to the development of cytochemistry.

The development of methods for the cytochemical detection of nucleic acids, in particular the Feilgen reaction and the Einarsop method, in combination with cytophotometry has made it possible to significantly clarify the understanding of cell trophism, the mechanisms and biological significance polyploidization (V. Ya. Brodsky, I. V. Uryvaeva, 1981).

In the first half of the 20th century. The functional role of intracellular structures is beginning to be elucidated. In particular, the work of D.N. Nasonov (1923) established the participation of the Golgi complex in the formation of secretory granules. G. Hogeboom proved in 1948 that mitochondria are the centers of cellular respiration. N.K. Koltsov was the first to formulate the idea of ​​chromosomes as carriers of molecules of heredity, and also introduced the concept of “cytoskeleton” into cytology.

The scientific and technological revolution of the mid-20th century led to the rapid development of cytology and a revision of a number of its concepts. Using electron microscopy, the structure was studied and the functions of previously known cell organelles were largely revealed, and a whole world of submicroscopic structures was discovered. These discoveries are associated with the names of K. R. Porter, N. Ris, W. Bernhard and other outstanding scientists. The study of cell ultrastructure made it possible to divide the entire living organic world into eukaryotes and prokaryotes.

The development of molecular biology has shown the fundamental commonality of the genetic code and the mechanisms of protein synthesis on nucleic acid matrices for the entire organic world, including the kingdom of viruses. New methods for isolating and studying cellular components, development and improvement of cytochemical studies, especially the cytochemistry of enzymes, the use of radioactive isotopes to study the processes of synthesis of cellular macromolecules, the introduction of electron cytochemistry methods, the use of fluorochrome-labeled antibodies to study the localization of individual cellular proteins using luminescent analysis, preparative methods and analytical centrifugation have significantly expanded the boundaries of cytology and led to the blurring of clear boundaries between cytology, developmental biology, biochemistry, molecular biophysics and molecular biology.

From a purely morphological science of the recent past, modern cytology has developed into an experimental discipline that comprehends the basic principles of cell activity and, through it, the foundations of the life of organisms. The development of methods for transplanting nuclei into enucleated cells by J. B. Gurdon (1974), somatic hybridization of cells by G. Barsk (1960), N. Harris (1970), B. Ephrussi (1972) made it possible to study the patterns of gene reactivation and determine the localization of many genes in human chromosomes and come closer to solving a number of practical problems in medicine (for example, analyzing the nature of cell malignancy), as well as National economy(for example, obtaining new crops, etc.). Based on cell hybridization methods, a technology for producing stationary antibodies from hybrid cells that produce antibodies of a given specificity (monoclonal antibodies) was created. They are already used to solve a number of theoretical issues in immunology, microbiology and virology. The use of these clones begins to improve the diagnosis and treatment of a number of human diseases, study the epidemiology of infectious diseases, etc. Cytological analysis of cells taken from patients (often after culturing them outside the body) is important for the diagnosis of some hereditary diseases (for example, xeroderma pigmentosum, glycogenosis) and studying their nature. There are also prospects for using the achievements of cytology for the treatment of human genetic diseases, the prevention of hereditary pathologies, the creation of new highly productive strains of bacteria, and increasing plant productivity.

The versatility of the problems of cell research, the specificity and variety of methods for studying it have currently led to the formation of six main directions in cytology:

1. Cytomorphology, which studies the features of the structural organization of a cell, the main research methods of which are various methods of microscopy, both fixed (light-optical, electron, polarization microscopy) and living cells (dark-field condenser, phase-contrast and fluorescent microscopy).
2. Cytophysiology, which studies the vital activity of a cell as a single living system, as well as the functioning and interaction of its intracellular structures; To solve these problems, various experimental techniques are used in combination with the methods of cell and tissue culture, microfilming and microsurgery.
3. Cytochemistry, which studies the molecular organization of the cell and its individual components, as well as chemical changes associated with metabolic processes and cell functions; Cytochemical studies are carried out using light microscopic and electron microscopic methods, cytophotometry, ultraviolet and interference microscopy, autoradiography and fractional centrifugation, followed by chemical analysis of various fractions.
4. Cytogenetics, studying the patterns of structural and functional organization of chromosomes of eukaryotic organisms.
5. Cytoecology, studying the reactions of cells to the influence of environmental factors and the mechanisms of adaptation to them.
6. Cytopathology, the subject of which is the study of pathological processes in cells.

Along with traditional ones, such new areas of cytology as ultrastructural cell pathology, viral cytopathology, cytopharmacology - evaluation of action are also developing in our country. medicines cytology methods on cell cultures, oncological cytology, space cytology, which studies the characteristics of cell behavior under space flight conditions.

Great Medical Encyclopedia 1979

Cell biology(cell biology, cytology) - the science of the cell.

Cellular biology is a branch of biology whose subject is the cell, the elementary unit of living things. A cell is considered as a system that includes individual cellular structures, their participation in general cellular physiological processes, and ways of regulating these processes. The reproduction of cells and their components, the adaptation of cells to environmental conditions, reactions to the action of various factors, and pathological changes in cells are considered. and the mechanisms of their death.

Cytology and Cell Biology

The term “Cell Biology” or “Cell Biology” in the second half of the 20th century replaced the original original term “Cytology”, which defined the science of the cell. Cytology belongs to a number of “lucky” biological disciplines, such as biochemistry, biophysics, and genetics, the development of which over the past 60 years has been particularly rapid (“biological revolution”) and has made fundamental changes in biology in the understanding of the organization and essence of life phenomena. Classical cytology, which in the beginning was mainly. descriptive morphological science, having absorbed the ideas, facts and methods of biochemistry, biophysics and molecular biology, has become a general biological discipline that studies not only the structure, morphology, but also the functional and molecular aspects of the behavior of cells as elementary units of living nature.

Although the first descriptions and ideas about the cell appeared more than 300 years ago, detailed study of cells was associated with the development of microscopy in the 19th century. At this time, the main descriptions of intracellular organization were made and the so-called cell theory (T. Schwann. R. Virchow), the main postulates of which are: cell - the elementary unit of living things; there is no life outside the cell (according to R. Virchow, “life is the activity of the cell, the characteristics of the first are the characteristics of the last”); cells are similar (homologous) in their structure and in their basic properties; cells increase in number and multiply only by dividing the original cells. The cell theory not only had a significant influence on the development of such general biological disciplines as histology, embryology and physiology, but also made a real revolution in medicine, showing that the basis of any diseases of the body is cellular pathology, i.e. change in functioning separate groups cells in organs and tissues.

A major role in the formation and development of domestic biology and, subsequently, cell biology was played by the scientific schools of researchers such as I.I. Mechnikov, N.K. Koltsov, D.N. Nasonov and others.

TO end of the 19th century century, many intracellular components were described (nucleus, chromosomes, mitochondria, etc.), mitosis was characterized as the only way of cell reproduction, and the chromosomal theory of heredity (cytogenetics) was created. At the same time and at the beginning of the 20th century, the interests of cytology were aimed at elucidating the functional significance of intracellular components (cytophysiology). The solution to these problems was helped by the development of such areas as cytochemistry, cell cultivation, associated with the introduction of new methodological techniques (fluorescence microscopy, quantitative cytochemistry, autoradiography, differential centrifugation, etc.).

A qualitative turning point in the analysis of cellular components and their functional significance was the introduction of electron microscopy in the 50s of the 20th century, which made it possible to study cells at the submicroscopic level. The combination of electron microscopic and molecular biological methods made it possible to closely link the study of the morphology of cell components with the identification of their biochemical characteristics and to establish their functional significance. It was in the middle of the 20th century that the term “cell biology” began to be used as a definition of a science that studies not only the structure of cells, but also the functional and biochemical characteristics of their structures and individual stages of cell life in general. At the same time, the cell cycle was discovered (the molecular sequence of events during cell reproduction), its regulation at the molecular level, and the functional and biochemical characteristics of many old and newly discovered intracellular structures were given.

The doctrine of the cell

Currently, from the standpoint of modern molecular biology, we can make the following definition of what a cell is: a cell is an ordered system of biopolymers (proteins, nucleic acids, lipids) and their macromolecular complexes, bounded by an active lipoprotein membrane, participating in a single set of metabolic (metabolic) and energy processes that maintain and reproduce the entire system as a whole.

Intracellular structural elements represent functional subsystems, or second-order systems. Thus, the cell nucleus is a system for storing, reproducing and implementing genetic information contained in the DNA of chromosomes; hyaloplasm (main plasma) - the system of the main intermediate metabolism and synthesis of monomers, as well as the synthesis of proteins on ribosomes; cytoskeleton - musculoskeletal system cells; vacuolar system - a system for the synthesis, modification and transport of some protein polymers and the formation of many cellular lipoprotein membranes; mitochondria are the organelles that supply energy to all cell functions through the synthesis of ATP; plastids of plant cells - a system for photosynthesis of ATP and synthesis of carbohydrates; The plasma membrane is the barrier-receptor-transport system of the cell.

It is important to emphasize that all these cell subsystems form a kind of conjugate unity that is mutually dependent. Thus, disruption of the nuclear function immediately affects protein synthesis, disruption of the structure and function of mitochondria stops all synthetic and metabolic processes, disruption of cytoskeletal elements stops intracellular transport, etc.

Modern biochemistry and molecular biology, which study the chemical processes underlying the life of cells, cannot do without information about the structures on which these processes occur; just as in cell biology, when studying structures and their functional significance, it is impossible to do without knowledge of the molecular processes occurring in these structures. Therefore, the term “molecular cell biology” is increasingly used in the titles of various manuals and textbooks.

The study of cell biology is of great practical importance: it is the study of the physiology of organisms, the use of cells in biotechnological developments, and the use of cell biology data in practical medicine. For example, information from the field of cell biology is necessary when studying malignant cell growth, for cytodiagnosis of the disease, for the use of stem cells, etc. Moreover, any human disease cannot be understood without the use of data from cell biology.

Outstanding Russian cytologists

I.I. Mechnikov (1845-1916) - famous Russian biologist and pathologist, one of the founders of experimental cytology and immunology, founder of a scientific school, honorary member of the St. Petersburg Academy of Sciences, one of the founders of the Pasteur Institute in Paris. In 1883, I.I. Mechnikov discovered the phenomenon of phagocytosis, put forward phagocytic theory immunity (1901); For his work on the study of immunity together with P. Ehrlich, he was awarded the Nobel Prize in 1908.

The scientific school of N.K. Koltsov (1872-1940) had a huge influence on the development of biology, genetics and cytology in our country. He was a researcher whose ideas were decades ahead of many discoveries that became the basis of modern concepts in genetics and cell biology. In 1903, N.K. Koltsov discovered the internal fibrillar system, which he defined as a skeletal cytoplasmic structure that determines the shape and movement of cells. Currently, this system is called the cytoskeleton; it consists of protein polymers from which microtubules and filamentous structures (microfilaments, intermediate filaments) are formed. Another important achievement of N.K. Koltsov was the foresight of the matrix principle of doubling hereditary structures. According to his ideas, small molecules of the nucleus assemble on an already existing template, and then “merge” into a polymer molecule, a copy of the template. At that time (1927) the macromolecules of DNA were not yet known, but the idea that a permanent, conserved hereditary matrix is ​​not destroyed or recreated, but is passed on from parents to offspring, was a great prediction. It can be considered that this statement by N.K. Koltsov was the beginning of the development of molecular biology. Many years of research on the shape and behavior of cells (cytoskeleton) and the matrix hypothesis are the greatest merit of N.K. Koltsov as a “prophet in his fatherland” in the development of biology. The great merit of N.K. Koltsov, in addition, lies in the fact that he trained a whole galaxy of his students-followers: geneticists, physiologists, embryologists and cytologists. These include V.V. Sakharov, B.L. Astaurov, S.S. Chetverikov, D.P. , A.S. Serebrovsky, G.I. Roskin and others. Now it is customary to talk about biological Russian school N.K. Koltsova. The Institute of Developmental Biology of the Russian Academy of Sciences now bears his name.

D.N. played a major role in the creation of domestic cytology. Nasonov (1895-1957). Dmitry Nikolaevich's works devoted to the study of the Golgi apparatus were highly appreciated by specialists and became classic. When studying the work of the Golgi apparatus D.N. Nasonov put forward a hypothesis about the leading role of this organelle in the cellular secretory process. Much later, with the help of electron microscopic autoradiography, this hypothesis was fully confirmed (Leblon, 1966) and became an axiom of the functional significance of this structure. In 1956, on the initiative of Dmitry Nikolaevich, the Institute of Cytology of the USSR Academy of Sciences was organized.

One of N.K. Koltsov’s students was G.I. Roskin (1882-1964), who worked with him since 1912. He studied skeletal and contractile structures in various cells, from unicellular organisms to the smooth and striated muscles of multicellular organisms. He concluded that contractile and supporting elements form very complex systems that provide motor and support functions - these systems were called statokinetic. This series of works is a continuation of the cytoskeleton studies begun by N.K. Koltsov.

From 1930 to 1964 G.I. Roskin headed the Department of Histology at the Moscow state university. Continuing to study the contractile elements of the cell, G.I. Roskin paid great attention to the study of the cytology of cancer cells, which led to the discovery of the anticancer drug crucin, which was used in the clinic for some time. Special attention to G.I. Roskin paid attention to the introduction of cytochemical methods into histology and cytology, which make it possible to localize certain polymers or individual amino acids in cells. At this time, the Department of Histology became a promoter of cytochemical methods, which were widely used not only in biological research, but also in medicine. Later V.Ya. Brodsky, student of G.I. Roskina, began to develop quantitative histochemical studies using special cytophotometric equipment. This led to the emergence of new biochemical and bio physical methods, which are widely used in cell biology.

A great contribution to the study of the structure and behavior of tumor cells was made by the works of Yu.M. Vasiliev (b. 1928) and his students. For many years, his school has been studying the mechanisms of movement of normal and tumor cells. He was the first to identify the role of the microtubule system and other cytoskeletal elements in determining the direction of migration of both normal and tumor cells. He heads the laboratory of mechanisms of carcinogenesis of the Oncological scientific center RAMS.

Yu.S. Chentsov (b. 1930) headed the department of cell biology and histology from 1970 to 2010. He is one of the founders of the Moscow school of electron microscopists. He and his students were the first to create a three-dimensional reconstruction of the centriole and describe its behavior in the cell cycle. Yu.S.Chentsov is one of the authors of the discovery of the nuclear protein framework (matrix); he showed that the nuclear matrix is ​​an integral part of interphase and mitotic chromosomes. Yu.S.Chentsov played a major role in the study of the ultrastructure of the cell nucleus and the mitotic chromosome. In his work on the study of mitochondria in muscle tissue, Yu.S. Chentsov became one of the authors of the discovery of the mitochondrial reticulum and a special structure - intermitochondrial contacts. (Daniel Mazia, 1912-1996), American cytologist who played a major role in the study of the processes of cell division and reproduction, in the study of the structure of the mitotic spindle and the reproduction of centrosomes. He considered the cell to be a supramolecular system consisting of many interconnected molecular systems.

Keith Porter (Keith Robert Porter, 1912-1997) - Canadian biologist, one of the founders of the electron microscopic approach in biology. He developed methods for producing ultrathin sections, methods for using coated grids in electron microscopy, and also proposed the use of osmium tetroxide for working with electron microscopic preparations. K. Porter is responsible for the discovery of cytoskeletal microtubules and endoplasmic reticulum, autolysosomes and bordered vacuoles. Thanks to him, the first leading journal in cell biology was founded, which is now called the Journal of Cell Biology.

George Palade (George Emil Palade, 1912-2008) - American biologist of Romanian origin. He discovered ribonucleic particles called Palade granules on the surface of the endoplasmic reticulum tanks. It was subsequently discovered that Palade granules are ribosomes associated with the endoplasmic reticulum. Palade worked extensively on the study of the vacuolar system and vesicular transport in the cell. In 1974 he was awarded the Nobel Prize.

Christian Rene de Duve (1917-2002) - Belgian cytologist and biochemist who discovered the existence of digestive organelles in cells - lysosomes. Nobel Prize winner (1974).

Albert Claude (1899-1983) - Belgian biochemist, thanks to whom cytology from a descriptive science became a functional science. He showed a direct connection between intracellular structures and the biochemical processes occurring in the cell, and participated in the introduction of biochemical and physical methods into cytology. A. Claude wrote that a cell is “an independent and self-sustaining unit of living matter, capable of accumulating, converting and using energy.” Nobel Prize winner (1974).

Recommended reading

Yu.S. Chentsov. Introduction to Cell Biology

Yu.S. Chentsov. Cytology: tutorial for universities and medical schools.

Alberts B., Bray D., Lewis J., Raff M., Roberts K., Watson J.D. Molecular biology of the cell

Molecular biology of cells. Translation from English / Edited by B. Alberts

Lodish H., Besk A., Zipursky S.L., Matsudaira P., Balximore D., Darnell J. Molecular cell biology.