Somites are spheres of epithelial cells that form sequentially along the anterior-posterior axis of the embryo through mesenchymal to epithelial transition of the presomitic mesoderm. [ ]

This is just here as a test because I lose it

Term information

database cross reference

uberon_slim, pheno_slim, vertebrate_core

axiom lost from external ontology

relationship loss: develops_from paraxial mesenchyme (TAO:0000942)[TAO]

relationship type change: part_of paraxial mesoderm (AAO:0010568) CHANGED TO: develops_from paraxial mesoderm (UBERON:0003077)[AAO]

relationship type change: OBO_REL:part_of trunk (TAO:0001115) CHANGED TO: develops_from trunk (UBERON:0002100)[TAO]


When the somite becomes segmented from the segmental plate, it is composed of an epithelial sac enclosing mesenchymal somitocoel cells. Thereafter the somite differentiates into two parts, the ventro-medial mesenchymal sclerotome and the dorso-lateral epithelial dermomyotome. This change in the epithelial somite depends on surrounding tissue [PMID:15906248]

depicted by

editor note

currently classified as an epithelial vesicle, consistent with EHDAA2 and Consider making 'somitic mesoderm' a separate term and correlate with regionalization processes. Consider moving ZFA term to 'trunk somite' as it is part of the trunk

external definition

Undifferentiated mesodermal components of early trunk or tail segments or metameres, derived from paraxial mesoderm; forms myotomes, sclerotomes and perhaps dermatomes. Kimmel et al, 1995.[TAO]

Post-cranial axial segments which form sclerotome and dermomyotome.[AAO]

has broad synonym

mesodermal cluster

has related synonym




epimere mesoderm

epithelial somite

somitic mesoderm

homology notes

(...) cephalocordates and craniates belong to a group known as Somitichordata. Somitichordate synapomorphies include (1) somites (...) (reference 1); The idea that the last common ancestor of bilaterian animals (Urbilateria) was segmented has been raised recently on evidence coming from comparative molecular embryology (reference 2).[well established][VHOG]