Probe:	Tbx20 probe2
Probe preparation:	Antisense labelled with digoxigenin RNA

Structure	Level	Pattern	Image	Note
TS13: heart	Strong	Graded	2A	Strong expression in the heart region. Graded expression along long axis, with highest levels caudally.
TS13: outflow tract	Present		2A	Small isolated domain of expression in the outflow tract.

Structure	Level	Pattern	Image	Note
TS15: heart	Strong	Graded	2B	Strong expression in the heart region.

Structure	Level	Pattern	Image	Note
TS17: heart	Strong	Graded	2C	Strong expression in the heart region.
TS17: atrioventricular canal	Strong		2C	Enhanced expression in atrioventricular canal and outflow tract.
TS17: outflow tract	Strong		2C	Enhanced expression in atrioventricular canal and outflow tract.

Structure	Level	Pattern	Image	Note
TS15: heart	Present	Graded	2D WT

Structure	Level	Pattern	Image	Note
TS15: heart	Present	Graded	2D Nkx2.5-/-	Both overall levels of expression and caudal-high gradient appeared normal in Nkx2-5 null embryos.

Structure	Level	Pattern	Image	Note
TS13: heart	Present		2E WT

Structure	Level	Pattern	Image	Note
TS13: heart	Present		2E Tbx5-/-	Authors report expression was roughly normal in Tbx5 null embryos.

Structure	Level	Pattern	Image	Note
TS13: heart	Present		2F WT

Structure	Level	Pattern	Image	Note
TS13: heart	Strong	Regionally restricted	2F RALDH-/-	Authors describe robust expression. Graded distribution of expression was flattened.

Structure	Level	Pattern	Image	Note
TS12: primitive heart tube cardiac muscle	Present	Regionally restricted	3A	Expression in the myocardial layer of the forming heart tube, with highest levels at the ventral side.

Structure	Level	Pattern	Image	Note
TS13: cardiac muscle tissue	Present	Regionally restricted	3B	Expression in both myocardium and endocardium. Higher expression in ventricular progenitors at outer compared with cells of inner curvature.
TS13: endocardial tube	Present	Regionally restricted	3B	Expression in both myocardium and endocardium. Higher expression in ventricular progenitors at outer compared with cells of inner curvature.
TS13: atrioventricular canal	Strong	Regionally restricted	3B	Highest levels in endocardium associated with endocardial cushions in atrioventricular canal and outflow tract.
TS13: outflow tract endocardial tube	Strong	Regionally restricted	3B	Highest levels in endocardium associated with endocardial cushions in atrioventricular canal and outflow tract.

Structure	Level	Pattern	Image	Note
TS14: outflow tract endocardial tube	Present		3C	Restriction to endocardium associated with forming endocardial cushions even more evident at E9.0 and E9.5.
TS14: atrioventricular canal cardiac muscle	Present		3C	Contiguous expression between ventricular myocardium and non-chamber myocardium in the atrioventricular canal.
TS14: primitive ventricle cardiac muscle	Present		3C	Contiguous expression between ventricular myocardium and non-chamber myocardium in the atrioventricular canal.
TS14: cardiac muscle tissue	Strong	Regionally restricted	3C	High expression in the earliest trabecular projections.

Structure	Level	Pattern	Image	Note
TS14: atrioventricular canal	Present	Regionally restricted	3D	Restriction to endocardium associated with forming endocardial cushions in atrioventricular canal and outflow tract even more evident at E9.0 and E9.5.
TS14: outflow tract endocardial tube	Present	Regionally restricted	3D	Restriction to endocardium associated with forming endocardial cushions in atrioventricular canal and outflow tract even more evident at E9.0 and E9.5.
TS14: cardiac muscle tissue	Strong	Regionally restricted	3D	High expression in the earliest trabecular projections.

Structure	Level	Pattern	Image	Note
TS15: atrioventricular endocardial cushion	Strong	Regionally restricted	3E	Strong expression in endothelial cells that have delaminated and migrated into the endocardial cushion extracellular matrix.
TS15: primitive ventricle cardiac muscle	Strong	Regionally restricted	3E	High expression in outer cell layer of ventricular myocardium. Very weak expression in differentiated trabeculae.

Structure	Level	Pattern	Image	Note
TS17: common atrial chamber	Present	Regionally restricted	3G	In the common atrium, expression largely restricted to the outer (ventral) curvature.

Structure	Level	Pattern	Image	Note
TS17: outflow tract endocardial cushion	Strong		3I	High levels of expression in endocardial cushions of the outflow tract.
TS17: cardiac muscle tissue	Trace	Widespread	3I	Very low expression thoughout the myocardial layer.

Structure	Level	Pattern	Image	Note
TS17: septum primum	Strong	Regionally restricted	3J	Strong expression in endothelial cells that have delaminated and migrated into the endocardial cushion extracellular matrix.
TS17: cardiac muscle tissue	Trace	Widespread	3J	Very low expression thoughout the myocardial layer.