Probe:	Hoxa2 probe13
Probe preparation:	Antisense labelled with digoxigenin RNA
Assay notes:	After whole-mount staining, embryos were post-fixed in 4% paraformaldehyde/0.2% glutaraldehyde before sectioning.

Structure	Level	Pattern	Image	Note
TS15: 2nd branchial arch mesenchyme derived from neural crest	Present	Regionally restricted	2E	Expression was detected in neural crest cells migrating from rhombomere 4 to the second branchial arch.
TS15: migrating neural crest	Present	Regionally restricted	2E	Expression was detected in neural crest cells migrating from rhombomere 4 to the second branchial arch.
TS15: 1st branchial arch	Absent		2E

Structure	Level	Pattern	Image	Note
TS15: 1st branchial arch mesenchyme derived from neural crest	Present	Regionally restricted	2F	Expression was detected in neural crest cells that migrate into the first arch from rhombomere 4 in the mutant.
TS15: migrating neural crest	Present	Regionally restricted	2F	Expression was detected in neural crest cells that migrate into the first arch from rhombomere 4 in the mutant.

Structure	Level	Pattern	Image	Note
TS15: 2nd branchial arch mesenchyme derived from neural crest	Present	Regionally restricted	2I	Expression was detected in neural crest cells in the second branchial arch.

Structure	Level	Pattern	Image	Note
TS15: 1st branchial arch mesenchyme derived from neural crest	Present	Regionally restricted	2J	Expression was detected in neural crest cells in the first arch from rhombomere 4. The labeled neural crest cells are adjacent to the mesodermal core and not to the vessels.