Somites

Somites

Somite

D'origine mésodermique, les somites sont des structures embryonnaires des Myomérozoaires, situées de part et d'autre du tube neural et de la chorde et composées d'unités répétées le long de l'axe antéro-postérieur de l'embryon.

Ils donnent naissance à deux structures essentielles :

  • le sclérotome, qui produit les vertèbres, les côtes et les cartilages axiaux (chez les vertébrés),
  • le dermatome, qui produit le derme et le myotome, à l'origine des muscles squelettiques du tronc et des membres (muscles striés).

À la fin de son développement, l'embryon possède 42 à 43 paires de somites, et le calcul de leur nombre permet donc de déterminer l'âge de cet embryon.

Sommaire

Voir aussi

Articles connexes

Liens externes

Bibliographie

Notes et références


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Regardez d'autres dictionnaires:

  • somites — Segmentally arranged blocks of mesoderm lying on either side of the notochord and neural tube during development of the vertebrate embryo. Somites are formed sequentially, starting at the head. Each somite will give rise to muscle (from the… …   Dictionary of molecular biology

  • somites — n. metamere, any of a number of segments that are arranged one next to the other in the body of certain animals (Zoology); layer of embryonic cells from which the muscles and vertebrae develop (Embryology) …   English contemporary dictionary

  • mesoblastic somites — Segmental divisions of embryonic mesoderm …   Dictionary of invertebrate zoology

  • somite — A body segment, especially of the abdomen [Chace and Hobbs, 1969]. Body segment, as in abdominal somites 1 6 [Poore, 2004]. Body segment, especially of the abdomen [Butler, T.H.]. Division of body (head, thorax, abdomen) with exoskeleton… …   Crustacea glossary

  • Somite — Transverse section of half of a chick embryo of forty five hours incubation. The dorsal (back) surface of the embryo is towards the top of this page, while the ventral (front) surface is towards the bottom …   Wikipedia

  • animal development — Introduction  the processes that lead eventually to the formation of a new animal starting from cells derived from one or more parent individuals. Development thus occurs following the process by which a new generation of organisms is produced by …   Universalium

  • thorax — Anteriormost division of the crustacean trunk [Brusca and Brusca, 2002]. Middle body region of eight somites bearing maxillipeds and pereopods [Poore, 2004]. see Cephalothorax [Butler, T.H.]. Tagma between cephalon and abdomen comprising anterior …   Crustacea glossary

  • abdomen — Posterior part of body, of six segments or somites, sometimes including tailfan [Poore, 2004]. Region of the body posterior to cephalothorax, consisting of six body segments and telson (see Fig. 13) [Hobbs and Jass, 1988]. That part of the body… …   Crustacea glossary

  • thoracomere — A segment of the thorax (regardless of whether any of these segments is fused to the head) [Brusca and Brusca, 2002]. Somite of thorax [Moore and McCormick, 1969]. Somite of thorax [McLaughlin, 1980]. Thoracic segments [Brusca and Brusca, 2002].… …   Crustacea glossary

  • cephalon — A term that refers to the head of a crustacean [Brusca and Brusca, 2002]. Anterior region of the body bearing the antennules, antennae, eyes, mandibles, maxillules, and maxillae [Holdich and Jones, 1983]. Anteriormost tagma, bearing eyes, mouth,… …   Crustacea glossary

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