Fig. 1. The Hox protein Antennapedia (Antp) is dynamically expressed in the pouch of the Drosophila wing disc.

a Antp staining (green, revealed with secondary anti-mouse coupled to Alexa488) with the historical 4C3 antibody used for the first description of Antp expression in the wing imaginal disc⁵. b Antp staining (green, revealed with secondary anti-mouse coupled to Alexa488) with the 8C11 antibody used in this study. The pouch region is outlined (yellow dotted line). Pictures on the right are 3D-plot projection made with Fiji to better highlight the zones with high and low levels of expression (the low-to-high expression level follows the cyan–white–green–yellow–red color gradient). The dorsal (D) and ventral (V) wing blade compartments are indicated. c Expression profile of Antp (green) in the wing disc at the larval stages 1 (L1), 2 (L2), and 3 (L3). The pouch region is outlined (yellow dotted line) and enlarged (red box) to better show the typical expression pattern that becomes progressively restricted to the ventral and dorsal sides. Yellow arrow depicts the peculiar profile in cells across the dorsal–ventral boundary of the pouch, which is apparent from L2 to mid-L3 larval stages. The pouch (p), hinge (h), and notum (n) regions are indicated in the L3 wing disc. This expression profile was observed in four independent experiments (n = 25). d Illustrative Antp staining (green) across different stacks (each stack is 0.2 µm) of a confocal acquisition of mid-L3 wing disc. Note the homogenous expression in the dorsal and ventral sides of the pouch (yellow dotted line) and the line of low- and few high-expressing cells along the dorsal–ventral boundary of the pouch (yellow arrows). e GFP staining (green) of the mimic-modified line homozygous for endogenous Antp-GFP. A L2 and L3 wing disc is shown. The pouch is outlined (yellow dotted line). f Expression of the UAS-mCherry reporter (magenta) driven by the P1-Antp promoter in front of Gal4 in mid-L3 wing disc. This driver shows more intense staining across the dorsal–ventral boundary of the pouch (yellow arrow). GFP and mCherry profiles were observed in two independent experiments (with a minimum n = 10).