Fig. 1

Lineage-Tracing Evidence for Hepatopancreatic Progenitors

(A–C) Ventral confocal images of control embryos at the 10 somite stage illustrating the accuracy of single-cell targeting by the laser. Tg(sox17:GFP)^s870 embryos were stained for GFP (gray) and uncaged fluorescein (red). A single endodermal cell was labeled in the region between somites 1 and 4 at three specific positions in the medio-lateral axis: the most medial cells (medial, [A]), cells immediately adjacent to the medial cells (lateral 1, [B]), and cells one cell away from the medial cells (lateral 2, [C]).

(D–I) Confocal projections of Tg(sox17:GFP)^s870 embryos at 50 hpf showing the progeny of the medial (D and G), lateral 1 (E and H), and lateral 2 (F and I) cells. Tg(sox17:GFP)^s870 embryos were stained for GFP (green), Insulin (blue), and uncaged fluorescein (red) (triple-positive cells appear white). Medial cells (D and G) mostly gave rise to pancreatic endocrine cells (arrows). Lateral 1 cells (E and H) gave rise to exocrine cells (double arrows), a small number of endocrine cells (arrows), as well as intestinal tissue (arrowheads) adjacent to the pancreas. Lateral 2 cells (F and I) gave rise to liver (asterisks), intestine (arrowheads), and exocrine cells (double arrows).

(J) 3D column graph tabulating the lineage-tracing data. Data in each column (%) were obtained by summing the number of embryos that showed incorporation into a given tissue type and normalizing it to the total number of embryos examined in each specific position: M, L1, and L2.

(K) Schematic diagram of Tg(sox17:GFP)^s870 expressing cells in the region between somites 1 and 4 with the bilateral position (red boxes) of cells that can give rise to liver and pancreas.