Probe:	Pax1 probe3
Probe preparation:	Antisense RNA
Visualized with:	Autoradiography

Structure	Level	Pattern	Image	Note
TS21: vertebral cartilage condensation	Present		2A/B	Expression was detected in more than 40 segmental domains along the developing vertebral column.
TS21: upper jaw mesenchyme	Present		2A/B
TS21: lower jaw mesenchyme	Present		2A/B
TS21: thymus primordium	Present		2A/B
TS21: rib cartilage condensation	Present	Regionally restricted	2A/B	Expression was detected in the proximal part of the ribs.
TS21: limb	Present	Regionally restricted	2A/B	Expression was detected in the limb buds.
TS21: axial skeleton	Present	Regionally restricted	2A/B	Expression is in the future sternum.

Structure	Level	Pattern	Image	Note
TS21: thoracic vertebral cartilage condensation	Present	Regionally restricted	2C/D	Expression stopped abruptly in the thoracic region of the mutant. In three embryos analyzed, only 14,17 and 18 expressing domains were found.

Structure	Level	Pattern	Image	Note
TS21: thoracic vertebral cartilage condensation	Present	Regionally restricted	2E/F	Expression stopped abruptly in the thoracic region.

Structure	Level	Pattern	Image	Note
TS17: 1st branchial pouch	Present		3A
TS17: forelimb bud	Present		3A
TS17: trunk paraxial mesenchyme	Present		3A	Expression was observed along the entire body axis from the occipital bone anlage to the newly generated somites in the tail region. Expression was stronger in the caudal half and a small area in the most cranial part of each segmental unit.

Structure	Level	Pattern	Image	Note
TS17: 1st branchial pouch	Present		3B	No difference in expression pattern was seen compared to wild-type.
TS17: forelimb bud	Present		3B	No difference in expression pattern was seen compared to wild-type.
TS17: hindlimb bud	Present		3B	No difference in expression pattern was seen compared to wild-type.
TS17: trunk paraxial mesenchyme	Present		3B	No difference in expression pattern was seen in the cervical region. Expression was seen up to the thoracic region and could not be observed in the lumbar, sacral or caudal regions.
TS17: trunk sclerotome	Present		3B	In seven Sd homozygotes the number of expressing sclerotomes starting from the proatlas anlage was 17 on average. This is similar to what was observed in day 13.5 wild-type embryos.

Structure	Level	Pattern	Image	Note
TS17: mesenchyme derived from head mesoderm	Present	Regionally restricted	5A	Expression is in the cranial part.
TS17: forelimb bud	Present		5A
TS17: trunk mesenchyme	Present	Regionally restricted	5A	Expression is in the lateral mesoderm.
TS17: tail paraxial mesenchyme	Absent		5A

Structure	Level	Pattern	Image	Note
TS17: trunk sclerotome	Present	Regionally restricted	5D	Expression can be seen up to the 18th sclerotome.
TS17: somite 16 sclerotome	Present		5D
TS17: somite 17 sclerotome	Weak		5D
TS17: somite 18 sclerotome	Weak		5D
TS17: somite 19 sclerotome	Absent		5D
TS17: somite 20 sclerotome	Absent		5D