Unsegmented field of paraxial mesoderm present posterior to the most recently formed somite pair, from which somites will form. Kimmel et al, 1995.[TAO]

uberon

somitogenic mesoderm, presumptive somite mesoderm, somitomeric mesoderm, PSM, unsegmented mesenchyme

It is reasonable to assume that the proximate invertebrate ancestor of the vertebrates had an amphioxus-like tail bud in its larval stage. This archetypal tail bud would have (...) (3) lacked any component of mesenchyme cells, (4) budded off new mesodermal segments directly, without any intervening zone of presomitic mesoderm (...). Then, early in vertebrate evolution, epithelium-to-mesenchyme interconversions (and the gene networks for effecting them) became prominent features of development. (...) In any case, conspicuous mesenchymal components tended to be added to the vertebrate tail bud itself. In addition, a mesenchymatous presomitic mesoderm (not a part of the tail bud proper) came to intervene between the tail bud and the forming somites.[well established][VHOG]

UBERON:0003059

• presumptive segmental plate

• somite border

• somite