invaginating stomatogastric nervous system precursor caudal vesicle of iSNSP VFB:FBbt_00001074 FBbt:00001074 caudal pouch of iSNSP fly_anatomy.ontology One of the three iSNSP pouches at embryonic stage 12, located in a intermediate position. It has around 25 cells. At stage 15, it has lost its epithelial structure and forms a cluster of cells. Half of these cells remains at the junction between the esophagus and proventriculus and develop into the proventricular ganglion. The other half migrates dorsally and anteriorly along the esophagus and possibly contributes to the frontal and/or hypocerebral ganglion.