part of adult proventriculus adult visceral muscle cell adult cardial muscle cell https://github.com/FlyBase/drosophila-anatomy-developmental-ontology/issues/24 FBbt:00003533 Cell that is part of the thin scattering of muscle fibers that covers the outer layer of the adult proventriculus (cardia). It is one cell thick, except at the anterior end of the proventriculus, where the muscle of the outer layer meets the muscle of the esophagus. fly_anatomy.ontology