part of develops from develops into anterior midgut primordium embryonic/larval midgut primordium gastric caecum fused midgut primordium gastric caecum primordium embryonic gastric caecum Primordium of the gastric caecum of the larva. There are four of these per midgut. They first become apparent as evaginations at the anterior end of the fused midgut primordium during stage 16. FBbt:00005629 fly_anatomy.ontology FBbt:00017027 anterior endoderm derivative