A structure created during embryogenesis when the lateral mesoderm splits into two layers - the outer (or somatic) layer becomes applied to the inner surface of the ectoderm, and with it forms the somatopleure.[WP].

http://upload.wikimedia.org/wikipedia/commons/2/28/Gray16.png

Gives rise to the paired appendages in jawed vertebrates. a persistent somatopleure through the redistribution and expansion of the lateral plate mesoderm is a synapomorphy for gnathostomes and a critical step in generating a novel developmental module with dramatic evolutionary potentia (Tulenko et al. 2012) http://burkelab.research.wesleyan.edu/current-projects/lamprey/

sources differ as to whether this is part-of or develops-from the LPM

uberon

UBERON:0004874

http://purl.obolibrary.org/obo/uberon.owl, http://purl.obolibrary.org/obo/cl.owl

• undifferentiated genital tubercle
• mesenchyme from somatopleure