Visualizing Drosophila Retina Ultrastructure

To visualize Drosophila retina ultrastructure, adult fly heads were dissected, fixed, dehydrated, and embedded in LR White resin (Electron Microscopy Sciences, Hatfield, PA) as described (Xu et al., 2015 (link)). Thin sections (80 nm) at a depth of 30–40 μm were prepared, and examined using a JEM-1400 transmission electron microscope (JEOL, Tokyo, Japan) equipped with a Gatan CCD (4k × 3.7k pixels, Palatine, IL). TEM of photoreceptor terminals was performed as described (Xu and Wang, 2019 (link)). Adult fly heads were dissected and fixed in 4% PFA. The laminas were further dissected by removing retinas, followed by fine fixation in 1% osmium tetroxide for 1.5 hr at 4°C. Thin sections (80 nm) were stained with uranyl acetate and lead citrate (Ted Pella) and examined using a JEM-1400 transmission electron microscope (JEOL, Tokyo, Japan) equipped with a Gatan CCD (4k × 3.7k pixels, Palatine, IL).