Something's fishy here--rethinking cell movements and cell fate in the zebrafish embryo

A recent paper has challenged the prevailing view that zebrafish blastomeres undergo extensive cell mixing and are unrestricted in their cell fates during early development. Here, we offer a model that resolves apparent contradictions between studies that have examined the origins of cell fate in the zebrafish embryo. The model reconsiders cell movements during epiboly, and how cell mixing, or the lack of it, can affect the predictability of cell fate.