From Big Medical Encyclopedia

EMBRYOLOGY EXPERIMENTAL (Greek embryon uterine fruit, germ + logos doctrine; lat. experimentum test, experience) — the section of embryology studying process of an embryogenesis in various experimental conditions for the purpose of search of ways and methods of purposeful impact on it. Use of experimental methods of a research allows to establish causes of infringement of a normal ontogeny, to reveal the conditions defining normal development of an organism and also to interfere actively with this process.

Separate experimental methods began to be used in embryology from the middle of 18 century. For development of the experimental direction in embryology E. Pflyuger's experiences had a certain value. However the greatest contribution to development of experimental methods of a research was made by the German scientist Ru (W. Roux, 1850 — 1924), to-rogo by right consider the founder of the experimental direction in embryology which is originally called by it development mechanics. The great influence on development of a recent trend was exerted by Driesch's researches (H. Driesch, 1867 — 1941), G. Shpemann, domestic scientific D. P. Filatov (1876-1943), etc.

Pilot studies in the field of embryology allowed to establish that the direction and result of development in the essentialest (emergence of specific features of an organism) depend on the genetic factors concluded in an oospore. An important role in determination of process is played by interactions of parts of a germ (as embryonic induction), and also the regulating influences of endocrine, nervous and immune systems.

It is experimentally established that conditions of the environment promote or prevent implementation hereditarily of a certain sequence of developments, accelerated or slow down development, can cause death of a germ, exert impact on specific features of an organism. For the purpose of establishment of influence of the environment on an embryogenesis investigated action chemical (including pharmaceuticals), physical (high temperature, ionizing radiation, etc.), mechanical, biological (bacteria, toxins, etc.) and immunological factors.

By means of experimental methods hypersensitivity of an embryo inherent in certain periods of determination to action of the damaging agents (critical periods) is revealed and temporary intervals of the greatest sensitivity to these agents for each body are defined (see the Germ).

Thanks to pilot studies the preformist-sky views of development which are reducing it only to growth already put in egg or a spermatozoon of materials of future germ are rejected. By means of an experiment it was succeeded to establish origins of separate parts of a germ, to track further development of blastomeres, movement of cellular material, process of a gastrulation.

In experimental embryology various methods are applied; such as division of a germ into parts and tracing of further development of these parts, change of parts of one germ to another, change of chemical structure of the environment, in a cut happens development, a method of marking (tag) of parts of a germ by harmless dyes, etc. The method of cultivation of fabrics and rudiments of bodies out of an organism allows to open not only mechanisms of a tsitodifferentsi-rovka and interaction of cells and fabrics in development, but also to estimate direct action of these or those agents, including pharmaceuticals, on the developing structures. By means of experimental embryology methods of storage (freezing) of sperm and ova, change of embryos are developed. The artificial insemination and change of embryos from highly productive females applied in livestock production allow to receive desirable genetic properties at posterity. In recent years widely apply methods of cultivation unfertilized and oospores, and also early germs. These researches open perspectives in fight against infertility at the person (e.g., at impassability of uterine tubes), and also help to distinguish the reasons patol. development of an organism. Experiments on transplantation to the woman of an oospore and receiving healthy posterity continue. Due to the high ductility and regenerator ability of germs at the first stages of crushing methodical approaches to division of one embryo are developed for receiving at animal several enzygotic twins with an identical genotype. Researches in the field of genetic engineering are of great interest (see), to-rye showed that in the period of an early embryogenesis at mammals the certain mechanisms capable to integrate alien genes into a genome take place, to provide their replication during a lineage and to cause an expression of alien genes in full accordance with the normal program of development at much later stages of ontogenesis according to their fabric or organ specificity.

See also Germ, Embryology. Bibliography: See bibliogr. to St. Embryology. O. V. Volkova.