The morphogenesis of the zebrafish eye, including a fate map of the optic vesicle

We have examined the morphogenesis of the zebrafish eye, from the hat optic vesicle at 16 hours post fertilization (hpf) to the functional hemispheric eye at 72 hpf, We have produced three-dimensional reconstructions from sem ithin sections, measured volumes and areas, and produced a fate map by labe ling clusters of cells at 14-15 hpf and finding them in the 24 hpf eye cup. Both volume and area increased sevenfold, with different schedules. Initia lly (16-33 hpf), area increased but volume remained constant; later (33-72 hpf) both increased. When the volume remained constant, the presumptive pig mented epithelium (PE) shrank and the presumptive neural retina (NR) enlarg ed. The fate map revealed that during 14-24 hpf cells changed layers, movin g from the PE into the NR, probably through involution around the margin of the eye. The transformation of the flat epithelial layers of the vesicle i nto their cup-shaped counterparts in the eye was also accompanied by cellul ar rearrangements; most cells in a cluster labeled in the vesicle remained neighbors in the eye cup, but occasionally they were separated widely. This description of normal zebrafish eye development provides explanations for some mutant phenotypes and for the effects of altered retinoic acid. (C) 20 00 Wiley-Liss, Inc.