somite
Sign in to saveThe somites (outdated term: primitive segments) are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryonic stage of somitogenesis, along the head-to-tail axis in segmented animals. In vertebrates, somites subdivide into the dermatomes, myotomes, sclerotomes and syndetomes that give rise to the vertebrae of the vertebral column, rib cage, part of the occipital bone, skeletal muscle, cartilage, tendons, and skin (of the back).
Key facts
- Embryology.Caption
- 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.
- Embryology.Image2
- Gray20.png
- Embryology.Caption2
- Dorsum of human embryo, 2.11 mm in length. (The older term primitive segments is used to identify the somites.)
- Embryology.CarnegieStage
- 9
- Embryology.Days
- 20
- Embryology.Precursor
- Paraxial mesoderm
- Embryology.GivesRiseTo
- Dermatome, myotome, sclerotome, syndetome
- Embryology.Name
- Somite
- Embryology.Latin
- somitus
- Embryology.Image
- Gray19 with color.png
via Wikipedia infobox
Article
14 sectionsContents
- Development
- Formation
- Notch signalling
- Mesenchymal-epithelial transition
- Specification
- Derivatives
- Dermatome
- Myotome
- Sclerotome
- Syndetome
- In arthropods
- See also
- References
- External links
The somites (outdated term: primitive segments) are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryonic stage of somitogenesis, along the head-to-tail axis in segmented animals. In vertebrates, somites subdivide into the dermatomes, myotomes, sclerotomes and syndetomes that give rise to the vertebrae of the vertebral column, rib cage, part of the occipital bone, skeletal muscle, cartilage, tendons, and skin (of the back).
The word somite is sometimes also used in place of the word metamere. In this definition, the somite is a homologously-paired structure in an animal body plan, such as is visible in annelids and arthropods.