part of adult midgut region R3ab 2020-04-17T13:30:20Z CCR Subregion at the anterior end of the adult midgut region R3 encompassing R3a and R3b. It is composed of copper cells (cuprophilic cells) interspersed with interstitial cells. The posterior region R3b is distinguishable from R3a by gene expression. adult midgut Cu region fly_anatomy.ontology FBbt:00049279 copper cell region of the adult midgut adult midgut copper cells region adult midgut region adult midgut region R3