Fig. 1: Design of the FlyVAB.

a Exploded view drawing of the FlyVAB (P1). FlyVAB (P1) was designed for imaging the adult Drosophila midgut across the ventral abdomen (VAB). It consists of the Base-1, the Lid, one R1, two R2, one S1, and one S2. The lid contains a groove of a height of 0.1/0.2 mm. b View of the assembled FlyVAB (P1). FlyVAB (P1) holds a coverslip in the Base-1. A U-shaped water-repelling pattern (green) was drawn on the coverslip to add one drop of HA solution. The adult Drosophila was placed into the platform after the removal of the wings. The squared region in b is enlarged in the upper right corner. c The two-step process to close the lid. First, the lid was aligned to the front edge of the coverslip, then vertically pressed until gently touching the dorsal abdomen cuticle. Second, the lid was pulled backward to the posterior part of the fly while the lid was pressed down until touching the coverslip. d Ventral view of the abdomen after closing the lid. The crop and midgut filled with food-stained with a blue dye were both visible through the transparent abdomen. e FlyVAB (P2) placed on an optical table, designed as a CO₂ anesthesia system. See also Supplementary Fig. 2. f View of the assembled FlyVAB (P1) and FlyVAB (P3) together. FlyVAB (P3) was designed as a link between FlyVAB (P1) and FlyVAB (P2) and it consists of the Base-2 and a removable S3. The PU tubing from the FlyVAB (P2) was placed above the fly through the S3 to deliver CO₂. The squared region in f is enlarged in the upper right corner. See also Supplementary Fig. 2. g Image of FlyVAB (P1) and (P3) placed on the microscope stage. The squared region in g is enlarged in the upper right corner.