Probe:	Irx1 cDNA8
Probe preparation:	Antisense labelled with digoxigenin RNA
Visualized with:	Alkaline phosphatase

Structure	Level	Pattern	Image	Note
TS17: primitive ventricle cardiac muscle	Present			Expression is present in the cardiomyocytes of the trabecules where the ventricular septum will be formed.

Structure	Level	Pattern	Image	Note
TS19: ventricle cardiac muscle	Present	Regionally restricted	2A	Expression is present in the cardiomyocytes surrounding the interventricular foramen, a region that will contribute to the ventricular conduction system.

Structure	Level	Pattern	Image	Note
TS19: interventricular septum	Present		3E , 3B	Expression is stronger in the trabecular component than the myocardial component and more pronounced on the left side than the right side.
TS19: interventricular septum endocardial lining	Absent		3E , 3B
TS19: lung	Present		3B

Structure	Level	Pattern	Image	Note
TS23: atrioventricular bundle	Present			Expression is present in the top of the septum where the antrioventricular bundle will develop.
TS23: impulse conducting system	Present	Regionally restricted		Expression is present in the longitudinally organized trabecules that will form the bundle branches.
TS23: interventricular septum	Present	Regionally restricted		Expression is present in the longitudinally organized trabecules that will form the bundle branches.

Structure	Level	Pattern	Image	Note
TS25: atrioventricular bundle	Present		4H , 4E	Expression is present in the top of the septum where the antrioventricular bundle will develop.
TS25: impulse conducting system	Present	Regionally restricted	4E , 4H	Expression is present in the longitudinally organized trabecules that will form the bundle branches.
TS25: interventricular septum	Present	Regionally restricted	4E , 4H	Expression is present in the longitudinally organized trabecules that will form the bundle branches.

Structure	Level	Pattern	Image	Note
TS21: phalanx pre-cartilage condensation	Present