prdm1a is expressed in multiple pharyngeal arch tissues and prdm1a-/- shows a reduction in expression in pharyngeal arch markers. A-D: In situ hybridization showing prdm1a expression in a 52-hpf embryo. A: Whole mount embryo in which the RNA probe was overdeveloped with BM purple and white lines indicate the plane of sectioning in the following panels. B: prdm1a is expressed in the developing neural retina of the eye (black arrows, e). C: The otic vesicle (ov) and an anterior endodermal pouch (ep). D: The developing pharyngeal tooth bud (pt) and mesenchyme of the 5th ceratobranchial (cb5). Molecular markers in the pharyngeal arch region in prdm1a mutants. E, F: dlx2a expression in the post-migratory neural crest in wildtype (E) and prdm1a mutants (F) shows an overall reduction in expression of dlx2a throughout the arch region in prdm1a mutants, but more strongly reduced posteriorly. G, H: barx1 expression in chondrogenic progenitors is slightly reduced in arch 2 and significantly reduced in arches 3-7 in prdm1a mutants (H) as compared to control (G). Bracketed area indicates pharyngeal arch region in wt/het and arrows indicate reduced expression domains in prdm1a-/-. I, J: neuroD expression in neurons of the cranial ganglia shows a reduction of expression in the trigeminal (anterior arrow) and posterior ganglia, including the lateral line ganglia (posterior arrow) in prdm1a mutants (J) as compared to control (I). K,L: nkx2.3 expression in the pharyngeal endoderm of wildtype (K) and prdm1a mutants (L). nkx2.3 is reduced in the posterior arch region in prdm1a mutants. Bracketed area indicates pharyngeal arch region. Anterior is to the left (A, E-L). The otic vesicle (ov) is labeled (E-L) as a reference point. cb5, ceratobrachical 5; ep, endodermal pouch; nc, notochord; ov, otic vesicle; pt, pharyngeal tooth; wt/het, wildtype/heterozygotes embryo.
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