Origin of the zebrafish endocrine and exocrine pancreas.

Here, we report a detailed fate map of the zebrafish pancreas at the early gastrula stage of development (6 hours postfertilization; hpf). We show that, at this stage, both pancreas and liver progenitors are symmetrically localized in two broad domains relative to the dorsal organizer. We demonstrate that the dorsal and ventral pancreatic buds can derive from common progenitor pools at 6 hpf, but often derive from independent populations. Endocrine vs. exocrine pancreas show a similar pattern of progenitors, consistent with descriptions of the dorsal bud being strictly endocrine and the ventral bud primarily exocrine. In general, we find that endocrine/dorsal bud progenitors are located more dorsally than the exocrine pancreas/ventral bud progenitors. Later in gastrulation (10 hpf), pancreas progenitors have migrated to bilateral domains at the equator of the embryo. Our fate map will assist with design and interpretation of future experiments to understand early pancreas development.