CELLULAR THEORY

From Big Medical Encyclopedia

CELLULAR THEORY — the theory combining ideas of a cell as to the main base and functional unit of all vegetable and animal organisms.

On To. t. all live organisms consist from cells (see), new cells are formed by division already existing, all cells are generally similar on chemical structure and metabolic processes, and life activity of an organism in general is caused by interaction of the cellular elements making this organism. V K. t. results of centuries-old studying of a structure of various live organisms are generalized.

In 1665 R. Hooke published the composition under the name «The Micrography or Some Physiological Descriptions of the Smallest Bodies Made by means of Magnifying Lenses», on the basis of studying of a structure of a stopper wrote to Krom that substance of a stopper is generally filled with air and that this air is completely concluded in the small boxes or cells separated from each other. The subsequent researches and A. Levenguka confirmed to M. Malpigi, N. Grew a cellular texture of plants. However for all these scientists the cell reflected only a nek-ry yacheistost of substance of fabric of plants; their attention was riveted only on a cellular cover.

By the beginning of 19 century idea of generality of a cellular texture of organisms began to extend, and in 1809 the fr. scientist Ge. Lamarck gave the formulation of generality of a cellular texture: «... any body does not may contain life if its compound parts do not represent cellular fabric and are not formed by cellular fabric». By the end of the first third of 19 century behind a cell began to recognize value not only as morfol., but also as fiziol, the element possessing an independent metabolism.

In 1838 M. Shleyden's article «Materials for phytogenesis» where he, proceeding from idea standard already of a cell as to the main base unit of plants, raised a question of formation of new cells was published and came to conclusion that each cell has a kernel. Bases To. t. were stated in T. Shvann's work «Microscopic examination about compliance in a structure and growth of animals and plants» (1839). T. Shvann showed that the cell is an elementary base unit of vegetable and animal fabrics that cells of animals and plants are homologous each other and similar on funkts, to value and that process of formation of cells causes growth, development and a differentiation of vegetable and animal fabrics.

To. t. was one of the largest generalizations of natural sciences of 19 century F. Engels mentioned To. t. among three major achievements of science of that period. He wrote: «Only since this opening there was on the firm soil a research of organic, live products of the nature — both a comparative anatomy and physiology, and embryology. The cover of a secret shrouding process of emergence and growth and structure of organisms was broken. The miracle, incomprehensible till that time, appeared in the form of the process happening according to the law, identical in essence for all metaphytes» { K. Marx and T. Engels, Half-N of SOBR. soch., 2 prod., t.20, p. 512).

The great influence on the subsequent development of the doctrine about a cell was exerted by R. Virkhov's work «Cellular pathology» (1858), in a cut an explanation patol, process was given from materialistic positions, i.e. its communication in an organism with morfol is shown. structures, with certain changes in structure of the cells. R. Virkhov finally approved idea that new cells arise only by division previous, and expressed it in an aphorism «each cell from a cell» («omnis cellula e cellula»).

Though in 1838 T. Shvann specified that To. t. it has to be applied to an explanation patol, processes, to it as well as I. Müller, F. Genle, R. Remak and other scientists, it was not succeeded to shake the humoral theory dominating then explaining diseases with «damage of juice». R. Virkhov's research laid the foundation for new science — pathology, edges also the wedge, medicine is a basis theoretical. Original positions of Virkhov that each cell arises from a cell that out of cells there is no life (though with certain amendments), were confirmed by further development of biology. However R. Virkhov incorrectly considered that patol, process in an organism is the sum of disturbances of life activity of separate cells, <i.e. especially local process. The cell was built in degree of an independent being owing to what the organism was considered not as whole and as the sum of cells. It led to the fact that in the second half of 19 century. To. t. gained more and more metaphysical character. End of this line of development To. t. the mechanistic theory of «the cellular state» of Gekkel was (E. The N of Haeckel), according to a cut an organism is compared to the state, and its cells with citizens. This theory destroyed idea of integrity of an organism. This direction was criticized by I. M. Sechenov, and O. Gertvig, A. G. Gurvich, M. Geydengayn, etc. is later.

In the second half of 19 century. To. t. it was used during the studying of the elementary organisms. G. Th. Siebold in 1841 for the first time formulated a concept about type of one-celled animals. Thus representation about one-celled was established and metaphytes, there was usual a comparison of protozoa to separate cells of metaphytes.

To the middle of the 50th of the last century the provision that the new growth of cells occurs by cellular division, was approved finally (see. Cell division ). However the first observations of mitotic division were accidental and sketchy. In 1875 E. Strasburger's work was published, in a cut it described mitosis (see) at a number of vegetable objects, and also division of cartilaginous cells and eggs at astsidiya. He claimed that indirect division at the most various organisms happens on the general patterns, however the separate moments of a mitosis and value of chromosomes remained for it not clear.

In 1882 Flemming for the first time applied the term «karyokinesis» in modern sense. It entered also the terms «direct» and «indirect division», «mitosis» and «amitotic division», «nuclear network», «chromatin», «achromatin», «equatorial plate» (see. Cell ). He paid special attention to changes of the chromatinic device and for the first time showed longitudinal splitting of chromosomes.

In the same years there is a detailed research of processes of maturing of sex cells and fertilization. By O. Gertvig (1875) it was actually proved that the essence of fertilization is merge of kernels of men's and female sex cells in a kernel of a zygote.

At the end of 19 — the beginning of 20 century studying of a cell begins with new positions — positions geneticists (see). In 1884 O. Gertvig and Strasburger put forward the idea that chromatin is the material carrier of heredity. This situation was in more detail developed by A. Veysman. Being guided by the data received during the studying meiosis (see), in particular on disclosure of sense of «conjugation of chromosomes», Seton (W. Sutton, 1902) gave tsitol, an explanation for Mendelian splitting (see. Mendel laws ).

N. K. Koltsov in 1934 one of the first put forward the idea about a chromosome as to a huge molecule, edges was confirmed 20 years later.

Broad use in the 50th of the electronic and microscopic equipment allowed to specify details of a structure of organoids, already known in light microscopy, and to describe new — a cytoplasmic reticulum (see. Endoplasmic reticulum ), lysosomes (see), etc. At the same time the homology of organellas in cells of different fabrics of one organism and in cells of organisms of various classes, types and kingdoms was shown. So To. t., arisen more than a century ago, obtained new, even more convincing evidence on subcellular and molecular levels of studying live.

See also Molecular biology , Cytogenetics , Cytology .



Bibliography: De Robertis E., Novinsky V. and Saes F. Cytobiology, the lane with English, M., 1973; L of e in and And. both Sikevits F. Struktura and function of a cell, lane with English, M., 1971; The Guide to cytology, under the editorship of A.S. Troshin, etc., t. 1, M. — L., 1965; Shvann T. Microscopic examinations about compliance in structure and growth of animals and plants, the lane with it., M. — L., 1939.


T. A. Zaletayeva.

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