Gal4 enhancer trap expression patterns in larval midgut. In all images, the anterior is toward the top and the posterior points towards the bottom. In B-F, the images are of the midgut junction region with the anterior midgut towards the top and acidic region towards the bottom. All size bars are 50 um except for the insert in C which is 10 um. A) The proventriculus is a large bulbous, multilayered portion of the foregut located at the junction of the foregut and midgut. bric-a-brac Gal4 expresses in the posterior within the inner layer of the proventriculus (thin arrow) and to a lesser extent within posterior cells of the outer endothelial layer (thick arrow). B) C135-Gal4 expresses within the Midgut Junction DH31 expressing cells (thick arrow) and the copper cells of the acidic region of the larval midgut (thin arrow). Expression can also be seen in tracheal precursor cells anterior to the Acidic region (arrow head). C) DJ717-Gal4 expresses in tracheal precursor cells (thick arrow and insert) as well as sporadically in the acid producing copper cells (thin arrow). D) CB30-Gal4 expresses in Midgut Junction DH31 expressing cells (thick arrow), tracheal precursor cells (thin arrow) and in circular muscles (arrow head). E) DJ761-Gal4 expresses in crypt cells (thick arrow) and in anterior midgut endothelial cells (thin arrow). F) c564-Gal4 expresses in Midgut Junction DH31 expressing cells (thick arrow) and throughout all cells in the endothelial lining of the larval midgut.