part of epithelial cell adult foregut cell of proventricular intermediate layer adult foregut epithelial cell adult proventriculus epithelial cell adult proventriculus epithelial zone 3 adult proventriculus zone 3 epithelial cell 2024-06-21T10:20:28Z PV3 cell FBbt:00059333 fly_anatomy.ontology Epithelial cell of the third zone of the adult proventriculus epithelium (King, 1988). These cells are shorter than the cells from the first and second zones, and are characterized by numerous mitochondria. They secrete the first layer of the peritrophic membrane (Zhu et al., 2024). There are approximately 450 of these cells in the adult proventriculus.