Fine structure and development of the retina of the grenadier anchovy Coilia nasus (Engraulididae, Clupeiformes)

A study of the morphogenesis of the grenadier anchovy retina was undertaken using light and electron microscopy. Five developmental stages from prelar vae 3 days after fertilization to adult fish were studied. In addition to t he general morphology of the eye and retina, special emphasis was given to the development of the photoreceptors and pigment epithelium (PE). The earl iest retinae showing structural features indicative of a functioning eye ar e pure cone retinae composed of rows of alternating long and short cones fo rming a transient, tesselated pattern. At this stage there is a conventiona l PE containing melanin. In older stages cone rows are separated by the new ly formed rods and by PE wedges filled with diffusely reflecting guanine cr ystallites. The findings are compared with the retinae of other engraulidid s and with the development of teleost retinae in general. Moreover, the obs erved structural changes are discussed with respect to the photic habitat c onditions of these anadromous fish that move between coastal waters, estuar y, and river. (C) 2001 Wiley-Liss, Inc.