part of develops from develops into ventral neurectoderm larval ventral nerve cord developing embryonic structure extended germ band embryo primordium ventral nerve cord primordium fly_anatomy.ontology ventral neuroectoderm ventral neuroderm primordium P3 venNeur FBbt:00005430 Primordium which is formed by the delamination of neuroblasts from the ventral neurogenic region. The first of five waves of delamination starts towards the end of embryonic stage 8. During stage 11, the mesectoderm loses contact with the outer surface and forms neuronal and glial precursors in the midline of this primordium. venNeurP3 AvenNeur FBbt:00005554 ventral neurectoderm FBbt:00000115 portion of tissue ventral ectoderm derivative