part of develops from embryonic stomatogastric nervous system caudal vesicle of tSNSP embryonic proventricular ganglion fly_anatomy.ontology VFB:FBbt_00005671 FBbt:00005671 Extended ganglion of the embryonic stomatogastric nervous system. Five to ten neurons are scattered along the axon bundle that extends from the paraesophageal ganglion and that by late embryogenesis grows further posteriorly onto the proventriculus. embryonic ventricular ganglion proventricular ganglion proventricular ganglion primordium anterior ectoderm derivative