Organogenesis

Organogenesis is the formation of the bodies in the process of embryonic development of the organism. The process of formation of authorities during ontogeny (see), i.e. ontogenetic organogenesis, studies embryology (see), and over the historical development of the form (phylogenetic organogenesis) - comparative anatomy.
Cm. also the Germ, Phylogeny.

Organogenesis (from the Greek. organon - body genesis - development, education)- the process of development or formation of organs of an embryo of the person and animals.
Organogenesis follows the earlier periods of embryonic development (see Embryo) - crushing eggs, gastropatia and comes after will be separated basic rudiments (bookmarks) organs and tissues. Organogenesis runs in parallel with the histogenesis (see), or the development of tissues. In contrast fabrics, each of which has its source any one of rudimentary organs, usually occur with the participation of several (two to four) different germs (see Embryonic sheets), giving rise to different tissue components of the body. For example, as part of the intestine wall epithelium lining the cavity of the body, and glands develop from internal embryonic leaf - endoderm (see), connective tissue, vascular smooth muscle tissue from mesenchyme (see), mesotheli covering serous membrane of intestine - from visceral piece of splanchnotomy, i.e. the average embryonic leaf - mesoderm, and nerves and ganglia body of neural Bud. The skin is formed with the participation of external embryonic leaf - the ectoderm (see), which is developing the epidermis and its derivatives (hair, sebaceous and sweat glands, nails and others), and dermatomes, of which occurs mesenchyma, differentiated connective the basis of the skin (the dermis). Nerves and nerve endings in the skin, as elsewhere,is derived neural Bud. Some bodies are formed from a single embryo, such as bone, blood vessels, lymph nodes from the mesenchyme; but here, in a bookmark grow derivatives rudiment of the nervous system - nervous fibers are formed nerve endings.
If the histogenesis is mainly in reproduction and specialization of cells, and also in the education of their intercellular substances and other non-cellular structures, the basic processes underlying organogenesis, are education embryonic leaves folds, vachiani, protrusions, swelling, uneven, the accretion or division (separation), as well as mutual germination multiple tabs.
A person organogenesis begins from the end of the 3rd week and ends on the whole by the 4th month of fetal development. However, the development of a number of provisional (temporary) organs of the fetus - of chorion and amnion, yolk SAC begins from the end of the 1st week, and some definitive (final) bodies are formed later than the other (for example, lymph nodes, starting with the last months of fetal development and before the onset of puberty). Cm. also Morphogenesis, Ontogenesis.