Probe:	ptc probe
Probe preparation:	Antisense labelled with digoxigenin RNA
Visualized with:	Alkaline phosphatase

Structure	Level	Pattern	Image	Note
TS15: pharynx epithelium	Present	Regionally restricted	1E	Expression within pharyngeal endoderm and in mesenchyme in close proximity to the Shh-expressing endoderm.
TS15: pharynx mesenchyme	Present	Regionally restricted	1E	Expression within pharyngeal endoderm and in mesenchyme in close proximity to the Shh-expressing endoderm.
TS15: 1st branchial pouch	Weak	Regionally restricted	1E	Expression dowregulated in most distal tips of first pharyngeal pouch.
TS15: 1st branchial arch mesenchyme	Strong	Regionally restricted	1E	More extensive expression in lateral arch mesenchyme of first arch.

Structure	Level	Pattern	Image	Note
TS15: pharynx epithelium	Present	Regionally restricted	1F	Expression within pharyngeal endoderm and in mesenchyme in close proximity to the Shh-expressing endoderm.
TS15: pharynx mesenchyme	Present	Regionally restricted	1F	Expression within pharyngeal endoderm and in mesenchyme in close proximity to the Shh-expressing endoderm.
TS15: 2nd branchial pouch	Weak	Regionally restricted	1F	Expression dowregulated in most distal tips of second pharyngeal pouch.
TS15: 2nd branchial arch mesenchyme	Strong	Regionally restricted	1F	More extensive expression in lateral arch mesenchyme of second arch.

Structure	Level	Pattern	Image	Note
TS15: pharynx epithelium	Present	Regionally restricted	1G	Expression within pharyngeal endoderm and in mesenchyme in close proximity to the Shh-expressing endoderm.
TS15: pharynx mesenchyme	Present	Regionally restricted	1G	Expression within pharyngeal endoderm and in mesenchyme in close proximity to the Shh-expressing endoderm.
TS15: 3rd branchial pouch	Absent		1G	Expression not detected in distal third pouch.
TS15: 3rd branchial arch mesenchyme	Weak	Regionally restricted	1G	Less extensive expression in lateral arch mesenchyme of third arch.

Structure	Level	Pattern	Image	Note
TS15: pharynx epithelium	Present	Regionally restricted	1H	Expression within pharyngeal endoderm and in mesenchyme in close proximity to the Shh-expressing endoderm.
TS15: pharynx mesenchyme	Present	Regionally restricted	1H	Expression within pharyngeal endoderm and in mesenchyme in close proximity to the Shh-expressing endoderm.
TS15: branchial arch mesenchyme	Weak	Regionally restricted	1H	Less extensive expression in mesenchyme surrounding future laryngeo/tracheal diverticulum.

Structure	Level	Pattern	Image	Note
TS17: pharynx epithelium	Present	Regionally restricted	1M	Expression expanded in endoderm and ventral mesenchyme.
TS17: pharynx mesenchyme	Present	Regionally restricted	1M	Expression expanded in endoderm and ventral mesenchyme.
TS17: 1st branchial groove ectoderm	Strong	Regionally restricted	1M	Expression upregulated in most lateral mesenchyme and in ectodermal cleft of first arch.
TS17: 2nd branchial arch mesenchyme	Strong	Regionally restricted	1M	Expression upregulated in most lateral mesenchyme and in ectodermal cleft of first arch.

Structure	Level	Pattern	Image	Note
TS17: pharynx epithelium	Present	Regionally restricted	1N	Expression expanded in endoderm and ventral mesenchyme.
TS17: pharynx mesenchyme	Present	Regionally restricted	1N	Expression expanded in endoderm and ventral mesenchyme.
TS17: 2nd branchial arch mesenchyme	Present	Regionally restricted	1N	Lower level of expression in lateral mesenchyme at level of second pouch.

Structure	Level	Pattern	Image	Note
TS17: pharynx epithelium	Present	Regionally restricted	1O	Expression expanded in endoderm and ventral mesenchyme.
TS17: pharynx mesenchyme	Present	Regionally restricted	1O	Expression expanded in endoderm and ventral mesenchyme.
TS17: 4th branchial arch mesenchyme	Present	Regionally restricted	1O	Lower level of expression in lateral mesenchyme at level of third pouch.

Structure	Level	Pattern	Image	Note
TS17: pharynx epithelium	Present	Regionally restricted	1P	Expression expanded in endoderm and ventral mesenchyme.
TS17: pharynx mesenchyme	Present	Regionally restricted	1P	Expression expanded in endoderm and ventral mesenchyme.
TS17: 4th branchial arch mesenchyme	Present	Regionally restricted	1P	Lower level of expression in lateral mesenchyme at level of fourth pouch.

Structure	Level	Pattern	Image	Note
TS19: 1st branchial pouch	Present	Widespread	1U	Expression throughout first pouch.
TS19: 1st branchial arch	Present	Regionally restricted	1U	Expression in surrounding mesenchyme and surface ectoderm of first arch.

Structure	Level	Pattern	Image	Note
TS19: 2nd branchial pouch	Present	Widespread	1V	Expression throughout second pouch.
TS19: 2nd branchial arch ectoderm	Present	Regionally restricted	1V	Expression in surrounding mesenchyme and surface ectoderm of second arch.
TS19: 2nd branchial arch mesenchyme	Present	Regionally restricted	1V	Expression in surrounding mesenchyme and surface ectoderm of second arch.

Structure	Level	Pattern	Image	Note
TS19: 3rd branchial arch mesenchyme	Present	Regionally restricted	1W	Expression restricted from most distal endoderm and mesenchyme of third arch and pouch.
TS19: 3rd branchial pouch endoderm	Present	Regionally restricted	1W	Expression restricted from most distal endoderm and mesenchyme of third arch and pouch.

Structure	Level	Pattern	Image	Note
TS19: 4th branchial arch mesenchyme	Present	Regionally restricted	1X	Expression restricted from most distal endoderm and mesenchyme of fourth arch and pouch.
TS19: 4th branchial pouch endoderm	Present	Regionally restricted	1X	Expression restricted from most distal endoderm and mesenchyme of fourth arch and pouch.