Probe:	Six2 cDNA1
Probe preparation:	Antisense labelled with digoxigenin RNA
Visualized with:	Alkaline phosphatase

Structure	Level	Pattern	Image	Note
TS13: head mesenchyme	Present	Regionally restricted	8A	First identified expression; expressed in a restricted mesodermal cell population at the anterior hindbrain level.

Structure	Level	Pattern	Image	Note
TS13: foregut diverticulum mesenchyme	Present	Regionally restricted	9A	Expression over the very anterior foregut region.

Structure	Level	Pattern	Image	Note
TS15: head mesenchyme	Present	Regionally restricted	8B	Prominent in frontal region; restricted rostral boundary; broad band extending caudally from hindbrain to cervical spinal cord.
TS15: 1st branchial arch	Present	Regionally restricted	8B	Expression in cells invading the medial part of arches.
TS15: 2nd branchial arch	Present	Regionally restricted	8B	Expression in cells invading the medial part of arches.
TS15: esophageal region mesenchyme	Present		8B	Expression in pharyngeal-oesophageal mesenchyme.
TS15: pharynx mesenchyme	Present		8B	Expression in pharyngeal-oesophageal mesenchyme.
TS15: mesenchyme derived from splanchnopleure	Present	Regionally restricted	8B	Expression in a restricted area of midgut mesenchyme.
TS15: midgut mesenchyme	Present	Regionally restricted	8B	Expression in a restricted area of midgut mesenchyme.

Structure	Level	Pattern	Image	Note
TS15: esophageal region mesenchyme	Present	Regionally restricted	9B	Expression in the anterior oesophageal region.

Structure	Level	Pattern	Image	Note
TS15: midgut mesenchyme	Present	Regionally restricted	11A	Expression in a narrow and anterioposterior limited region of the midgut mesoderm.
TS15: midgut epithelium	Absent		11A

Structure	Level	Pattern	Image	Note
TS17: genitourinary system	Present	Regionally restricted	8C	Expression in developing cervical nephrotomes; also in surrounding mesenchymal cells.
TS17: mesonephros	Present		8C
TS17: mesonephros mesenchyme	Present		8C
TS17: nephrogenic cord	Present		8C

Structure	Level	Pattern	Image	Note
TS17: esophagus mesenchyme	Strong		9C	Strong expression in most of mesenchyme of the pharyngeal-oesophageal region.
TS17: pharynx mesenchyme	Strong		9C	Strong expression in most of mesenchyme of the pharyngeal-oesophageal region.
TS17: esophagus epithelium	Absent		9C	No expression in endodermally-derived parts of the tube.
TS17: pharynx epithelium	Absent		9C	No expression in endodermally-derived parts of the tube.

Structure	Level	Pattern	Image	Note
TS17: 1st branchial arch	Present	Regionally restricted	10A	Expression in a medial string of cells invading the 1st and 2nd branchial arches; also in a small region of 1st arch ectoderm, between mandibular and maxillary swellings.
TS17: 2nd branchial arch	Present	Regionally restricted	10A	Expression in a medial string of cells invading the 1st and 2nd branchial arches; also in a small region of 1st arch ectoderm, between mandibular and maxillary swellings.

Structure	Level	Pattern	Image	Note
TS17: hindbrain	Present	Regionally restricted	10B	Expression in a small area of neuroectoderm in the anterior hindbrain (corresponds to myelencephalon).
TS17: head mesenchyme	Present		10B

Structure	Level	Pattern	Image	Note
TS17: nephrogenic cord	Present	Regionally restricted	12A	Expression in mesenchyme of posterior nephrogenic cords.

Structure	Level	Pattern	Image	Note
TS19: head mesenchyme	Present	Regionally restricted	8D	Expression in a band of cervical mesodermal cells.
TS19: trunk somite	Present	Regionally restricted	8D	Expression extends further into ventro-lateral part of some thoracic somites.
TS19: mesonephros	Present	Regionally restricted	8D	Expression localized to mesenchyme of mesonephric tubules.
TS19: genital tubercle	Present	Regionally restricted	8D	Expression in mesenchyme of genital eminence.
TS19: forelimb bud	Present	Regionally restricted	8D	Expression in forelimb mesenchyme.

Structure	Level	Pattern	Image	Note
TS19: mesonephros	Present	Regionally restricted	12B	Expression in mesonephric tubules.
TS19: genital tubercle	Present		12B

Structure	Level	Pattern	Image	Note
TS19: handplate	Present	Regionally restricted	7A' (wm)	Narrow band of expression along anterior margin, extending distally.

Structure	Level	Pattern	Image	Note
TS19: handplate	Present	Regionally restricted	7A' (sxn)	Stronger expression ventrally than dorsally.

Structure	Level	Pattern	Image	Note
TS19: hindlimb bud	Present			Authors report that expression in the hindlimb is similar, but a few hours delayed.

Structure	Level	Pattern	Image	Note
TS20: hand	Present	Regionally restricted	7B' (wm)	Expression expands posteriorly; approximately the same anteroposterior domain as Six1; outlines the shapes of digits.

Structure	Level	Pattern	Image	Note
TS20: hand	Present	Regionally restricted	8E	Expression expands posteriorly; approximately the same anteroposterior domain as Six1; outlines the shapes of digits.

Structure	Level	Pattern	Image	Note
TS20: hand	Present	Regionally restricted	7B' (sxn)	Authors report that expression remains stronger ventrally.

Structure	Level	Pattern	Image	Note
TS20: esophagus mesenchyme	Present	Regionally restricted	9D	Expression in oesophageal region limited to regions of supporting smooth muscles and connective tissue. Expression starts to fade; remaining expression in restricted mesenchymal cell population.

Structure	Level	Pattern	Image	Note
TS20: midgut mesenchyme	Present	Regionally restricted	11B	Expression in region of midgut mesenchyme corresponding to the gastric-duodenal area; may correspond to the pyloric stomach.

Structure	Level	Pattern	Image	Note
TS20: metanephros	Present	Regionally restricted	12C	Expression over undifferentiated mesenchymal part of metanephros surrounding the urethric buds; not in urethric buds.

Structure	Level	Pattern	Image	Note
TS21: hand	Present	Regionally restricted	7C' (wm)	Expression flanking digit cartilage condensations.

Structure	Level	Pattern	Image	Note
TS21: hand	Present	Regionally restricted	7C' (sxn)	Expression flanking digit cartilage condensations.

Structure	Level	Pattern	Image	Note
TS22: genital tubercle	Present	Regionally restricted	12E	Very localized expression over genital tubercle mesenchyme.

Structure	Level	Pattern	Image	Note
TS22: hand	Present	Regionally restricted	7D' (wm)	Expression pattern complementary to Six1.

Structure	Level	Pattern	Image	Note
TS22: hand	Present	Regionally restricted	7D' (sxn)	Expression is mainly ventral (strong) but also dorsal (weak) to phalangeal elements of the digits.

Structure	Level	Pattern	Image	Note
TS23: head mesenchyme	Present	Regionally restricted	13A/B	Expression over some of head membrane bones, mostly derived from neural crest; weak expression in a few head muscles.

Structure	Level	Pattern	Image	Note
TS24: esophagus	Weak			Expression largely diminished in the oesophagus, stomach and kidney.
TS24: metanephros	Weak			Expression largely diminished in the oesophagus, stomach and kidney.
TS24: stomach	Weak			Expression largely diminished in the oesophagus, stomach and kidney.