part of develops from head head mesoderm derivative multicellular structure esophageal visceral muscle primordium embryonic/larval esophageal visceral muscle Region of visceral muscle that is associated with the late embryonic or larval esophagus (Campos Ortega and Hartenstein, 1997). It is composed only of circular muscle fibers (Campos Ortega and Hartenstein, 1997). fly_anatomy.ontology FBbt:10005369