To visualize Drosophila retina ultrastructure, adult fly heads were dissected, fixed, dehydrated, and embedded in LR White resin (Electron Microscopy Sciences) as described [67 (link)]. Thin sections (80 nm) prepared at a depth of 30–40 μm 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, USA).
TEM of photoreceptor terminals was performed as described [73 (link)]. Adult fly heads were dissected in 4% PFA and the retinas were removed. The dissected lamina was fixed in a solution with 4% PFA and 2.5% glutaraldehyde for 2 h on ice, followed by fixation in 1% osmium tetroxide for 1.5 h at 4°C. Tissues were then dehydrated in a series of ethanol dilutions at 4°C (10-min wash in 10, 25, 40, 55, 70, 85, 95, and 30-min wash in 100% ethanol for 5 times). Samples were gradually infiltrated with 2 ratios of ethanol and Eponate 12 (Ted Pella), finally going into 3 changes of pure resin. Samples were allowed to infiltrate in pure resin overnight on a rotator and embedded in Eponate 12 resin (Ted Pella). 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, USA).
TEM of photoreceptor terminals was performed as described [73 (link)]. Adult fly heads were dissected in 4% PFA and the retinas were removed. The dissected lamina was fixed in a solution with 4% PFA and 2.5% glutaraldehyde for 2 h on ice, followed by fixation in 1% osmium tetroxide for 1.5 h at 4°C. Tissues were then dehydrated in a series of ethanol dilutions at 4°C (10-min wash in 10, 25, 40, 55, 70, 85, 95, and 30-min wash in 100% ethanol for 5 times). Samples were gradually infiltrated with 2 ratios of ethanol and Eponate 12 (Ted Pella), finally going into 3 changes of pure resin. Samples were allowed to infiltrate in pure resin overnight on a rotator and embedded in Eponate 12 resin (Ted Pella). 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, USA).
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