Cell mosaic patterns in the native and regenerated inner retina of zebrafish: Implications for retinal assembly

In part because of its laminar organization and morphologically distinct ce ll populations, the vertebrate retina has often been used as a system for i nvestigating the assembly of neural structures. The retinas of adult teleos t fish, because they grow throughout life and can regenerate following an i njury, provide an especially attractive model system for such investigation s. In an effort to provide a quantitative foundation for testing hypotheses regarding the mechanisms of pattern formation during growth and regenerati on of the vertebrate retina, nearest neighbor and auto-correlation analyses were used to examine the mosaic patterns of eight inner retinal cell group s in the native and regenerated retina of adult zebrafish. In both native a nd regenerated retina, the mosaic patterns of most inner retinal cells are non-random. However, regenerated mosaics tend toward significantly lower ne arest neighbor distances, less orderly patterns, and more variable radial l ocations than their native retina counterparts. The individual cell groups in both native and regenerated inner retina are likely to be spatially dist ributed independently. The results support the hypotheses that, in the adul t zebrafish: 1) distinct inner retinal cell groups of native retina are als o present in regenerated retina; 2) the assembly of inner retinal cell mosa ics is controlled by non-random spatial organizing mechanisms during develo pment, growth, and regeneration; and 3) the spatial organization of cell mo saics is disrupted during regeneration. The results suggest that retinal re generation may represent a spatially disrupted recapitulation of retinal de velopmental mechanisms. J. Comp. Neurol. 416:356-367, 2000. (C) 2000 Wiley- Liss, Inc.