Distinct roles for Hnf1ba in regulating β-cell numbers and ventral pancreas specification. (A) β-Cell nuclei numbers from 80 and 125 hpf wild-type and hnf1bas430 mutants, indicating that at either stage, hnf1bas430 mutants have significantly fewer β-cells. hnf1bas430 mutants (125 hpf) have significantly fewer β-cells than 80 hpf wild-type embryos. Error bars represent s.d. (B-G) Fluorescent confocal microscopy of Tg(ptf1a:eGFP)jh1 80 hpf wild type (B-D) and 125 hpf hnf1bas430 mutant (E-G) pancreas stained for insulin antibodies, SV2 antibodies and DAPI to mark β-cells (red), endocrine cells (white) and nuclei (blue), respectively. Three-dimensional rendering of red and green channels showing an hnf1bas430 mutant at 125 hpf with a larger pancreas (E) than wild-type (B). (C,F) Magnification (8×) of B and E (red and white channels only) to show mildly disorganized islet cells. (D,G) Z-focal plane of C and F (with all channels) demonstrating moderately reduced β-cell number in the hnf1bas430 mutant islet. For a more severe example, see supplementary material Fig. S2. (H-M) Three-dimensional rendering of 52 hpf Tg(ptf1a:eGFP)jh1 (pancreas, green) foregut endoderm in wild-type (H), hnf1bahi2169 mutants (I) and hnf1bas430 embryos (J) stained for Pdx1 to mark the duodenal intestine and cadherin to mark the endoderm epithelium. In contrast to hnf1bahi2169 (I), Pdx1 expression (arrowheads) in the intestine and dorsal pancreatic islet (I) is not lost in hnf1bas430 embryos (J). (K-M) Three-dimensional rendering of 80 hpf Tg(ptf1a:eGFP)jh1; Tg(lfabp:dsRed)gz2 (pancreas, green; liver, red) foregut endoderm in wild-type (K) hnf1bahi2169 (L) and hnf1bas430 embryos (M) stained for cadherin showing specific loss of ventral pancreas in hnf1bas430 hypomorphic mutants. Unlike the hnf1bahi2169 (L), liver (L) and swimbladder (SB) are not lost in the hnf1bas430 embryos.