Fig. 1. Microphotograph of trout retina section (PE+PRL, pigment epithelium and photoreceptor layer; OLM, outer limiting membrane; ONL, outer nuclear layer; OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer; NFL, nerve fibre layer; ILM, inner limiting membrane). The trout retina is completely devoid of blood vessels. Numbers denote thickness ± S.D.(N=3) in µm of the respective layers. For GCL and NFL the combined thickness of the two layers is given. Insert: Microphotographs of eel retina as an example of a teleost retina with intraretinal vascularization. Large blood vessels visible on ILM reach into the retina to OLM. Bars, 100 µm, 50 µm (insert).