The following primary antibodies were used: rabbit anti-Cg25C (Zang et al., 2015 (link); 1:5,000), rabbit anti-Ndg (Wolfstetter et al., 2009 (link); 1:2,000), guinea pig anti-Tango1 (Lerner et al., 2013 (link); 1:1,000), rabbit anti-Sec16 (Ivan et al., 2008 (link); 1:1,000), rabbit anti-GM130 (cat#ab30637, 1:500; Abcam), rabbit anti-COPII (Sec23, cat#PA1-069A, 1:500; Thermo Fisher Scientific), and goat anti-Gmap (Riedel et al., 2016 (link); 1:500). Secondary antibodies were IgG conjugated to Alexa Fluor 488, Alexa Fluor 555, or Alexa Fluor 647 (1:200; Thermo Fisher Scientific). Larvae were predissected in PBS by turning them inside out, fixed in PBS containing 4% PFA, washed in PBS (3 × 10 min), blocked in PBT-BSA (PBS containing 0.1% Triton X-100 detergent, 1% BSA, and 250 mM NaCl), incubated overnight with primary antibody in PBT-BSA in 4°C, washed in PBT-BSA (3 × 20 min), incubated for 2 h with secondary antibody in PBT-BSA at room temperature, and washed in PBT-BSA (3 × 20 min) and PBS (3 × 10 min). Tissues were finally dissected and mounted on a slide with a drop of DAPI-Vectashield (cat#H-1200; Vector Laboratories). For blood cell staining and imaging, blood cells from two to five larvae were bled inside a 20-µl drop of PBS on a glass slide and allowed to attach to the slide for 10 min before fixation.