invaginating stomatogastric nervous system precursor intermediate vesicle of iSNSP One of the three iSNSP pouches at embryonic stage 12, located in a intermediate position. It has around 25 cells. At late stage 14, it has lost its epithelial structure and forms an elongated cluster that merges anteriorly, where the frontal ganglion will develop. The anterior part of the vesicle contributes to the frontal ganglion, whereas the posterior part gives rise to the hypocerebral ganglion. fly_anatomy.ontology VFB:FBbt_00001073 intermediate pouch of iSNSP FBbt:00001073