Brain–ring gland complex was dissected out in cold phosphate-buffered saline (PBS) buffer and fixed in 4% paraformaldehyde for 20 min (90 (link)). Brain–ring gland complex was stained overnight at 4°C with chicken anti-GFP (1/500; Life Technologies), and rat anti-Pvr (91 (link)) (1/500; a gift from B. Shilo). Secondary antibodies 488 anti-chicken (1/500) and 647 anti-rat (1/500) were purchased from Invitrogen. For DNA and nuclei staining, we used Hoechst (1/1000) for 10 min at room temperature. We set up the tile scan with the micrometer-thick Z stack on an LSM880 Zeiss microscope with 40× oil objective. Images were acquired with a resolution of 1024 × 1024.