Effects of reduced vwa1 on the development of pharyngeal cartilage. (A) Endodermal pouch in Tg (nkx2.3:EGFP) embryos. At about 38 hpf, when the endodermal pouch is almost fully formed, no apparent difference was observed in the pharyngeal pouch in vwa1 morphants (right) compared with uninjected morphants (left). (B)vwa1 knockdown causes a reduction in cranial neural crest cell numbers. At about 19 hpf, when neural crest cells migrate to the cranial area, the expression of crestin in vwa1-knockdown embryos was not obviously different from that of uninjected control embryos (a and b). At 30 hpf, when migration of neural crest cells is complete, dlx2a was expressed in similar domains, but the area of these domains was reduced significantly in vwa1 morphants (c and d). At 48 and 72 hpf, when the cranial neural crest has differentiated into pharyngeal chondrocytes, sox9a was expressed in similar domains, but the areas of these domains were reduced significantly in vwa1 morphants (e–h). These data show that, in vwa1 morphants, neural crest cells generally could migrate to the pharyngeal arch and specify to chondrocytes, but their numbers were reduced.
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