part of develops from start stage end stage adaxial cell somite muscle pioneer ZFA:0001086 zebrafish_anatomy non migratory adaxial cells Cells that develop from adaxial cells that express engrailed and do not migrate completely to the lateral surface of the myotome, and instead extend from the notochord to the lateral surface of the somite, at the level of the future horizontal myoseptum. TAO:0001086 muscle pioneers muscle cell segmentation:5-9 somites hatching:pec-fin