part of adult midgut epithelium adult proventriculus intermediate layer adult proventriculus epithelium adult proventriculus epithelial zone 4 2024-06-21T09:03:07Z FBbt:00059327 The section of the adult midgut epithelium inside the proventriculus that extends from the end of the foregut cuticle to the fold between the intermediate and outer layers of the proventriculus (King, 1988). This is the anteriormost segment of the midgut epithelium inside the proventriculus. PV4 region fly_anatomy.ontology