Antibody:

anti-Pbx1b

Structure	Level	Pattern	Image	Note
TS16: 4th branchial arch ectoderm	Present	Regionally restricted	4A , 4B	Nuclearly localized expression most prominent in mesenchyme, endoderm and ectoderm of the fourth arch.
TS16: 4th branchial arch mesenchyme	Present	Regionally restricted	4A , 4B	Nuclearly localized expression most prominent in mesenchyme, endoderm and ectoderm of the fourth arch.
TS16: 4th branchial pouch endoderm	Present	Regionally restricted	4A , 4B	Nuclearly localized expression most prominent in mesenchyme, endoderm and ectoderm of the fourth arch.
TS16: branchial arch	Present	Graded	4B , 4A	Authors report graded expression anterior to 4th branchial arch region.

Structure	Level	Pattern	Image	Note
TS17: branchial arch ectoderm	Strong	Regionally restricted	4C , 4D	Highest levels of nuclear expression in surface ectoderm and pouch endoderm throughout the pharyngeal region.
TS17: branchial pouch endoderm	Strong	Regionally restricted	4C , 4D	Highest levels of nuclear expression in surface ectoderm and pouch endoderm throughout the pharyngeal region.
TS17: 3rd branchial arch mesenchyme	Present	Regionally restricted	4C , 4D	Mesenchymal localization of expression more prominent in subsets of mesenchyme in arches three and four. Expression least prominent in mesenchyme surrounding the third pouch in region where thyroid/parathyroid primordia form.
TS17: 4th branchial arch mesenchyme	Present	Regionally restricted	4C , 4D	Mesenchymal localization of expression more prominent in subsets of mesenchyme in arches three and four. Expression least prominent in mesenchyme surrounding the third pouch in region where thyroid/parathyroid primordia form.