A FATE MAP FOR THE 1ST CLEAVAGES OF THE ZEBRAFISH

A FATE map depicts how lineages from a defined blastomere will be restricted to particular tissues. In the amphibian Xenopus laevis, the early blastomeres of the embryo have traceable lineages1-4. However, it has been thought that mixing of the blastomeres of Brachydanio rerio prevents them from giving rise to a fate map5-10. For this reason the zebrafish has been used as an example of a class of embryos, including mammals, which apparently exhibit little fate until later in embryogenesis. The amphibia were the exception. We report here the use of fluorescent dyes on very-high-molecular-mass carriers to trace a fate map from the first three cleavages of the zebrafish embryo to the three principal adult body axes: the first cleavage defines dorsal-ventral; the second cleavage, left-right; and the third, anterior-posterior.