Fig. 4

Complementary EphrinB1 and EphB3b Expression Controls Hepatoblast Positioning and Cell-Shape Changes in Liver Bud Formation

(A-F‴) At 22 hpf, EphrinB1 and EphB3b expression largely overlaps in future hepatoblasts and the LPM (A-A‴). Complementary expression of both factors coincides with the start of liver budding: EphrinB1 in hepatoblasts and EphB3b in the gut and LPM (B–B‴). At 32 hpf, hepatoblasts are located more posteriorly and medially compared with controls in MO-ephrinb1 (C-D‴), in MO-ephb3b (E-E‴), and upon conditional UAS:ephrinb1^EC expression (F-F‴). (A-F′) ventral views of confocal projections, anterior to the top; (A″–F″) transverse sections of the foregut, as indicated by the dashed line in (A′-F′), and matching schematics (A‴-F‴); yellow arrowheads specify the midline and white brackets the length of the Prox1 domain.

(G–I) Cell shapes were determined with EphrinB1-staining at 32 hpf (see Figure 1F). Quantification of hepatoblast shape in control, MO-ephrinb1, and MO-ephb3b embryos: (G) L/W distribution for one representative bud; (H) proportion of elongated cells per bud; SEs are shown; and (I) orientation of elongated hepatoblasts with respect to the anteroposterior axis. ^∗p < 0.05.

See also Figure S2.