Transmission Electron Microscopy (TEM)
The anterior segment was removed immediately after eyeball extraction, and immersed in 2.5% glutaraldehyde solution for retina separation. Then retinas were immersed in 2.5% glutaraldehyde for 1 h, and fixed in 1% osmic acid for 1 h. Next, retinas were dehydrated with ethanol, embedded with Epon epoxy resin, followed by treated with electron staining, uranium acetate, lead citrate (each for 15 min). Retinas were then observed and photographed under TEM (HT7700; Exalens, Hitachi Plant Technologies Ltd, Tokyo, Japan).