Portion of the middle of the three primary germ layers of the embryo that resides on the periphery of the embryo, is continuous with the extra-embryonic mesoderm, splits into two layers enclosing the intra-embryonic coelom, and gives rise to body wall structures[MP].
Comment:
[homology-note] "A ventrolateral zone of amphioxus mesoderm grows down to surround the gut. Homology of this zone to the lateral plate mesoderm of vertebrates is supported by site of origin and fate.[well established][VHOG]" xsd:string {date_retrieved="2012-09-17", external_class="VHOG:0000118", ontology="VHOG", source="DOI:10.1073/pnas.97.9.4449 Shimeld SM and Holland PW. Vertebrate innovations. PNAS (2000)", source="http://bgee.unil.ch/"}