Fig. 5: Loss of hox13 paralogues in the zebrafish resulted in defects in the cloacal region.
From: Co-option of an ancestral cloacal regulatory landscape during digit evolution
a–h, Confocal microscopy of phalloidin-labelled cloacal regions of wild-type and hox13 mutant zebrafish at 6 days post-fertilization shown in a single channel (a–d) and with pseudo-colouring (e–h). Pseudo-colouring indicates hindgut (blue), pronephric duct (yellow) or fused ducts (green). The phenotypes reported here were consistent across individuals collected from four independent crosses of triply heterozygous parents. a,e, Wild-type fish have adjacent but distinct openings for the hindgut (blue line) and pronephric duct (yellow line) (n = 10), as do hoxd13a mutants (n = 6) (b,f). c,g, hoxa13a;hoxa13b double mutants exhibited fusion of the hindgut and pronephric duct and a single opening (green line) (n = 4). d,h, hoxa13a;hoxa13b;hoxd13a triple mutants showed connection of the hindgut and pronephric duct to form a large shared lumen (green) with a single opening (green line) (n = 4). The consistent phenotypes observed in the double and triple mutant classes were significant when each class was individually compared with wild type using Fisher’s exact test (wild type, n = 10; mutant, n = 4; P = 9.9 × 10−4). Scale bar, 30 μm.
