EMBRYOLOGY

From Big Medical Encyclopedia

EMBRYOLOGY (Greek embryon a uterine fruit, a germ + logos the doctrine) — science about patterns of embryonic development of an organism. AA. the person and live-bearers is studied by the period of pre-natal development of an organism. AA. oviparous — the period of development before hatching of egg; AA. amphibians — the period of development which is coming to an end metamorphosis (see). Allocate also E. plants. In a crust. time E. the person and animals is studied by not only the period of pre-natal development, but also the period of post-natal development, in Krom processes of a histogenesis, organogenesis and morphogenesis continue (e.g., formation of a reproductive system).

Instead of the term «embryology» the sciences of the name «ontogenetika», «development mechanics», «dynamics of development», «physiology of development» which were more answering to contents, etc. were offered as if. However to a crust. time the term «embryology» is still used.

Subject E. animals and the person studying of all processes happening in an organism during its development including the periods of a progenesis actually is, fertilisations (see), embryonic development (see), fetal development (see. Fruit ), and also post-natal period.

AA. investigates as the general patterns of phylogenesis which are shown in development of all metazoans (from sponges and coelenterates to vertebrata and the person), and features of ontogenetic development of the person and representatives, separate types, classes and animal species. Studying of development of a complete organism is carried out by the analysis of development (both the whole organism, and its parts) at the different levels; at the same time formation of bodies and systems, changes of fabric, cellular and subcellular structures is traced. Main theoretical basis E. biogenetic law is (see).

Process of an ontogeny of the person is considered as historically (phylogenetic) the caused process. A certain sequence of the main stages of embryonic development repeats at all metazoans. So, formation of an axial complex of rudiments, chords, a neurotubule, formation of visceral furrows testify to a community of an origin of the person and chordate animals; segmentation and a differentiation of a mesoderm, education at a germ of the person of originally cartilaginous, and then bone skeleton reflect evolutionary changes of a skeleton among vertebrata; the vitellicle, amnion, an allantois are inherited by the person from reptiles; formation of a placenta is characteristic of the person and placental mammals; powerful development of a trophoblast and early isolation of an extraembryonic mesoderm are observed at germs of the person and subhuman primates. However especially the prematurity and specialization of an extraembryonic mesoderm, the latest short circuit of the front end of a neurotubule and some other features of an embryogenesis are observed only at the person.

Founders of embryology consider Hippocrates and Aristotle (4 century BC). Hippocrates and his followers approved preexistence in fatherly and maternal «seed» of all parts of future fruit (see Preformizm), i.e. development came down only to quantitative changes (growth without differentiation). This look was resisted by more progressive doctrine of Aristotle about consecutive formation of bodies in the course of an embryogenesis (see Epigenesis). In 1600 — 1604 Fabritsy gave the description of development of a germ of the person, detailed for the time, and chicken. Base for allocation E. as sciences U. Garvey's work «Researches about origin of animals» was (1651), in a cut egg for the first time was considered as a source of development of all animals. At the same time U. Garvey, as well as Aristotle, considered that development of vertebrata happens generally by epigenesis, claiming that any part of future fruit «does not exist in egg urgent, but all parts are in it potentially». M. Malpigi (1672) who found by means of a microscope bodies of a germ of a chicken at early stages of his development adjoined preformistsky representations, to-rye dominated in science almost to the middle of 18 century. K. F. Wolf in works «The theory of origin» (1759) and «About formation of intestines at a chicken» (1768 — 1769) convincingly proved that nucleus growth is a development. Having disproved preformistsky representations, it laid the foundation of embryology as sciences about development. In 1827. K. M. Ber opened and described ova of mammals and the person. In the classical work «About Stories of Development of Animals» (1828 — 1837) he for the first time tracked the main lines of an embryogenesis of a number of vertebrata, specified entered by X. I. Zander a concept about germinal leaves as about the main embryonal bodies also tracked their development. He proved that development of the person happens in the same sequence, as development of other vertebrate animals. Law K. M. Rem (see the Germ) about similarity of development of different classes of vertebrata had huge value for progress of embryology as sciences, in this regard he by right is considered the ancestor of modern embryology.

In creation evolutionary comparative E., based on Ch. Darvin's theory, edges, in turn, was of great importance for the statement and further justification of theory of evolution (see), the exclusive role belongs to domestic researchers I. I. Mechnikov and A. O. Kowalewski. They established that development of all types of invertebrates passes through a stage of isolation of germinal leaves, homologous to germinal leaves of vertebrata, and it demonstrates unity of an origin of all types of metazoans. The big contribution to development of evolutionary embryology was made by the Russian scientists A. N. Severtsov who created the theory of a filembriogenez, P. G. Svetlov who developed theories of critical periods of ontogenesis and a metamerism of chordates (see. Germ ). The end 19 — the beginning of 20 century were marked by active development of experimental methods, the big merit in development to-rykh belongs it. to scientists E. Pflyuger, Ru, domestic scientists D. P. Filatov, M. M. Zavadov-sky, P. Ivanov, N. V. Nasonov, etc. The big contribution to development of science was made by A. A. Zavarzin, N. G. Hlopin, P. K. Anokhin, B. L. Astaurov, G. A. Schmidt, B. P. Tokin, A. G. Knorre, D. M. Golub, A. N. Studitsky, L. I. Falin, etc.

Depending on tasks and methods of a research distinguish the general, comparative, ecological and experimental E. (see Embryology experimental).

In the beginning E. developed generally as morfol. the science also had descriptive character (descriptive embryology). The method an iiya and descriptions allowed to establish to a nablyuda that development goes from simple to difficult, from the general to the particular, from homogeneous to diverse. On the basis of the descriptive works devoted various biol. to types and classes, there was a comparative embryology, edges allowed to reveal a certain similarity between development of animals and the person. Afterwards embryologists began to study not only development of a form and structure, but also formation of functions of bodies and fabrics. The ecological embryology studies the factors providing existence of a germ, i.e. feature of its development in certain conditions of the environment and a possibility of adaptation in case of their change.

Modern E. characterizes complex morfofiziol. approach to studying and interpretation of development. Along with methods of observation and the description in a crust, time difficult methods of a research are widely applied: microscopic, microsurgical, biochemical, immunological, radiological, etc. Their variety is caused by close connection E. with other sciences. AA. it is inseparable from genetics (see. Genetics of the person , Medical genetics) since ontogenesis (see) as a matter of fact reflects sale of the mechanism of heredity; it is closely connected with cytology (see) and histology (see) because complete development of an organism is based on set of processes of reproduction, migration, a differentiation, death of cells, interactions between cells. One of the main problems of histology — the doctrine about a histogenesis — is at the same time a part of embryology. AA. studies process morfol. differentiations (formation of specialized cells) and a chemical differentiation (the chemical organization) a peck, patterns of exchange processes in development of an organism. On the basis of close interrelation with cytology, molecular biology and genetics there was a new complex industry of biology — developmental biology. Great value progress E. had for development of anatomy (see) and histology. AA., studying changes of chemical structure and exchange processes of the developing structures (chemical E.) and also formation of functions (embriofiziologiya), uses data of biochemistry (see) and physiology (see).

Tasks E. not only the explanation of the phenomena and detection of their patterns, but also an opportunity to exercise control of development of an organism are. So, knowledge and methods E. have the direct appendix in the national economy, in particular livestock production, fish a vodstvo, silkworm breeding, are used for studying of influence of the environment on development of an organism, form a basis for work on an introduction, reorganization of biocenoses, etc. The most important for the person is use of achievements E. in medicine. Medical E. it is more and more allocated in independent science and is one of theoretical fundamentals of preventive medicine. Development of medical aspects modern E. plays an important role in the solution of such problems as regulation of birth rate, infertility, organ and tissue transplantation, tumoral growth, immune responses of an organism, phisiological and reparative regeneration, reactivity of cells and fabrics, etc. Researches in the area E. are of great importance in disclosure of a pathogeny of various malformations (see). Such important problems E., as growth and a differentiation of cells, are closely connected with questions of regeneration, a carcinogenesis, an inflammation, aging. Fight against prenatal and child mortality to a great extent depends on the solution of cardinal problems of embryology.

In modern embryology the great value is attached to a research of processes of a progenesis, and also search of ways of management of a progenesis and embryogenesis that is possible only at interpretation of the mechanisms controlling reproductive function and providing a homeostasis of germs of the person and mammals. These mechanisms represent difficult interaction of the genetic, epigenomny, internal and external factors defining the temporary and space sequence of an expression of genes and, respectively, a cytodifferentiation and a morphogenesis; the important part in the course of an embryogenesis is assigned to neuroendocrinal and immune systems, biologically active agents, etc. The research of mechanisms of regulation of a normal and pathological embryogenesis at various levels of the organization (organ, fabric, cellular, chromosomal) can help with research of ways of management of an ontogeny of animals and the person, and also with development of effective methods of prevention of inborn malformations and a pas tolite. states. Much attention is paid to a research of system mother — extraembryonic bodies — a fruit. Genetic features of a placenta of the person and its specific changes at hereditary diseases are studied; the research of an amniotic fluid for the purpose of diagnosis of diseases in the prenatal and post-natal periods is conducted. Works on cultivation of in vitro of ova and germs and transplantation of early germs of «foster mother» open perspectives of recovery of genital function at tube infertility. These researches allow to understand mechanisms of fertilization and development in the doimplantatsionny period, to analyze pathology of development, to estimate direct action on a germ of various factors, including pharmaceuticals, and also allow to come to the decision such obshchebiol. problems as cytodifferentiation. Researches on testing of the pharmaceuticals, chemical substances polluting the environment for the purpose of identification of their possible embriotoksichesky and teratogenic action are conducted. Search of the drugs (vitamins, antitoxins, etc.) stopping teratogenic effect of this or that substance is conducted. The researches in the field of genetic engineering (see) directed to intervention in structure and function of a genome of formative cells allow to cause changes genome (see) germs of mammals that in the future will give the chance to receive the animals deprived of undesirable signs and having the set properties. Thanks to development of these methods there will be an opportunity to create organisms — producers used in medicine biol. substances, such as hormones of the person, an antiserum, etc. and also to model nek-ry hereditary diseases of the person.

Problems of embryology in the USSR are developed at Institute of developmental biology of N. K. Koltsov of Academy of Sciences of the USSR, Ying-those evolutionary morphology and zooecology of A. N. Severtsov by Academy of Sciences of the USSR, Ying-those experimental medicine of the USSR Academy of Medical Sciences. Ying-those morphology of the person of the USSR Academy of Medical Sciences, and also at departments of histology and embryology of high fur boots and medical in-t of Moscow, Leningrad, Novosibirsk, Simferopol, Minsk. Tashkent, etc.

In many countries function scientific about-va anatomists, in to-rye also embryologists enter. In the USSR exists All-Union about-in anatomists, histologists and embryologists.

In our country the magazines reflecting problems E are issued.: since 1916 — «Archive of anatomy, histology and embryology», since 1932 — «Achievements of modern biology», since 1970 — «Ontogenesis», etc. (it is detailed see Anatomy). Abroad there are following main magazines devoted to problems E.: «Archiv fur Entwicklungsmechanik der Organismen» based by V. Py, «Biological Bulletin», «Journal of Experimental Zoology», «Journal of Embryology and Experimental Morphology», «Developmental Biology», etc.

Since 1949 the international congresses and conferences on embryology are regularly convoked. On the XI International congress of anatomists in Mexico City in 1980 new edition was accepted embryological nomenclature (see), the Russian option the cut is prepared by the Soviet morphologists.

Teaching embryology in the USSR is conducted at departments of histology and embryology medical and vt. in-t, on biological f-takh of high fur boots, at departments of anatomy and physiology of pedagogical in-comrades

Sm. also Anatomy , Histology .



Bibliography:

History — Blyakher L. Ya. History of embryology in Russia (from the middle of XVIII to the middle of the 19th century), M., 1955; Ginzburg V. V., Knorre A. G. and Kupriyanov V. V. Anatomy, histology and embryology in St. Petersburg — Petrograd — Leningrad, the Short sketch, L., 1957, bibliogr.; Needham D. History of embryology, the lane with English, M., 1947.

Textbooks, guides, main works — Bodemer U. Modern embryology, the lane with English, M., 1971, bibliogr.; Brashe Zh. Biochemical embryology, the lane with English, M., 1961, bibliogr.; Volkova O. V. and Baking M. I. Embriogenez and age histology of internals of the person, M., 1976; O. E. Immunologiya's Elms of an embryogenesis, M., 1962, bibliogr.; Dyban A. P. Sketches of pathological embryology of the person. L., 1959; 3ussm and N of M. Developmental biology, the lane with English, M., 1977; Ivanov P. P. Guide to the general and comparative embryology, L., 1945; Carlson B. Fundamentals of embryology on Pettena, the lane with English, t. 1 — 2, M., 1983; Knorre A. G. Short sketch of embryology of the person, L., 1959; it, Embryonal histogenesis. L., 1971; The Pathophysiology of pre-natal development, under the editorship of N. L. Garmasheva, L., 1959; Petten B. M. Embryology of the person, the lane with English, M., 1959; Stanek I. Embryology of the person, the lane with slovatsk., Bratislava, 1977; Tokin B. P. General embryology, M. 1977; Falin L. I. Embryology che loveka, Atlas, M., 1976; An analysis of development, ed. by B. H. Williera. the lake, Philadelphia — L., 1955; Are at L. B. Developmental anatomy, Philadelphia, 1965; Hamburger V. A manual of experimental embryology, Chicago, 1960; Lang-man J. Medizinische Embry ologie, Stuttgart, 1976; Nelsen O. E. Comparative embryology of the vertebrates, N. Y., 1953; Patten B. M. a. Carlson B. M. Foundations of embryology, N. Y., 1974; Pflugfelder O. Lehrbuch der Ent-wicklungsgeschichte und Entwicklungsphy-siologie der Tiere, Jena, 1962; Toivonen S. Primary embryonic Induction, L., 1962; Schumacher G. - H. Embryonale Entwicklung des Menschen, Stuttgart, 1974; Snell R. S-Clinical embryology for medical students, Boston — Toronto, 1983; ThomasJ. B. Introduction to human embryology, Philadelphia, 1968.

Periodicals — Archive of anatomy, histology and embryology, L. — M, since 1931 (1917 — 1930 — the Russian archive of anatomy, histology and embryology); Acta embryologiae et morphologiae experi-mentalis. Palermo, since 1957; Archives diatomic, d*hist ologie et d'embryologie, Strasbourg, since 1922; Developmental Biology, N. Y., since 1959; Excerpta medica. Sect. 1. Anatomy, Anthropology, Embryology and Histology, Amsterdam, since 1947; Journal of Embryology and Experimental Morphology, L., since 1953.

O. V. Volkova.

Яндекс.Метрика