Fig. 6

A–E Lateral views of phenotypically wildtype A–C zebrafish embryos and representative han^S6 mutants (D–F) at 3 dpf. Note the abnormal phenotype of the yolk extension (representative reference wildtypes in B) in han^S6 mutant embryos (asterisks in D, E); the increasing autofluorescence of the ventral yolk is possibly caused by the progressive disorganization of the yolk tissue. SPIM-based live imaging of hand2:EGFP transgene expression that depicts mesothelial progenitors over the posterior yolk and yolk extension (wildtype reference in C) documents disorganized and only partially migrated mesothelial progenitors (arrowheads in F). G Quantification of hand2:EGFP-expressing cells in wildtype versus hand2 MO-injected embryos (morphants) over time (days post-fertilization). The left graph depicts the total amount of hand2:EGFP+ cells in an embryo (including heart and pectoral fin field), the right graph the hand2:EGFP+ in the trunk region (boxed area in schematic). See Supplementary Fig. 8 for Imaris analysis. Source data are provided as a Source Data file. H–Jhan^S6 in the background of drl:creERT2;hsp70l:Switch (H), wt1a:EGFP (I), and hand2:EGFP (J). Visceral peritoneum is disorganized around the internal organs (pointed out with white arrows) and the body wall and the associated parietal peritoneum are malformed (pointed out with yellow arrows) in han^S6 mutants compared to wildtype controls. Gut (g), liver (li), pancreas (pa), pronephric duct (pd), and yolk (y). Nuclei in blue (DAPI). Scale bars A, D 250 μm, B, C, E, F 125 μm, and H–J 50 μm.