Fig. 1: The PG is a two-cell layer organ surrounded by a BM.
a, a’ The PG is organized into a dorsal and ventral layer. Dotted lines in the ventral layer image outline the trachea (a). 3D visualization of the ring gland (a’) composed of the PG (prothoracic gland), the corpora allata (CA), and the corpora cardiaca (CC). The aorta and trachea are indicated. b-b” Maximal projection of prothoracicotropic hormone (PTTH) staining (b) and two Z-sections revealing that PTTH neurons project their axons at the midline of the PG (arrowheads in b’ and b”). n ≥ 10 independent experiments (c) Synaptic PTTH boutons reveal PTTH in the presynapse and Torso in the postsynapse. nexperiment ≥ 3. d, d’ Expression of trol-GFP in the BM plane and in a lateral plane (d). The XZ section (d’) facilitates the observation of the trol-GFP dots. These dots (indicated by arrowheads) are CIVICs. nexperiment ≥ 10. e Z-sections reveal that the adherens junction proteins Arm and ECad, the septate junction markers Cora, Dlg1, as well as βPS, are uniformly distributed along the PG cell membranes. nexperiment ≥ 10. f Heatmap of Syt1-GFP in an XZ section of a PG cell. Flip-out Syt1 clones were generated by crossing the heat shock Flipase (hsFLP); Act > CD2>Gal4 line with UAS-Syt1-GFP. Following heat shock, CD2 is excised in random cells, enabling Syt1-GFP expression under Act-Gal4 control, here abbreviated as hsFLP; Act»Syt1-GFP. The quantification, shown below, is made across ROI boxes appearing in dotted lines, nclones = 7 (see Methods). Data are presented as mean ± 95% CI and were subjected to the Friedman test followed by Dunn’s multiple comparison tests (ns not significant, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001). Source data are provided as a Source Data file. White scale bars: 20 μm; yellow scale bar: 5 μm. g Schematic representation of a PG dorsal layer and XZ cut.
