Antibody:	Anti-CAII
Detection system:	Biotinylated secondary antibody/[Strept]avidin coupled to horseradish peroxidase

Structure	Level	Pattern	Image	Note
TS15: cardiac muscle tissue	Absent		1a
TS15: endocardial cushion	Present	Regionally restricted	1b , 1a	Expression was detected in most of the prismatic or cubic cells in the endocardium of the atrioventricular cushions. The endocardial cells were uniformly labeled.

Structure	Level	Pattern	Image	Note
TS15: cardiac muscle tissue	Absent		1d , 1e , 1c
TS15: endocardial cushion	Present	Regionally restricted	1d , 1e , 1c	Expression was detected in most of the prismatic or cubic cells in the endocardium of the atrioventricular cushions. The endocardial cells were uniformly labeled.

Structure	Level	Pattern	Image	Note
TS15: cardiac muscle tissue	Absent		1f
TS15: endocardial cushion	Present	Single cells	1f	In the distal part of the conotruncus, label was only seen in a few endocardial cells.

Structure	Level	Pattern	Image	Note
TS17: heart	Present	Regionally restricted	2b , 2a	Expression was detected in atrioventricular cushion mesenchymal cells.
TS17: cardiac muscle tissue	Absent		2a , 2b
TS17: endocardial lining	Present	Regionally restricted	2a , 2b	About 15% of cubic endocardial cells had positive signal.

Structure	Level	Pattern	Image	Note
TS17: bulbus cordis rostral half	Present	Regionally restricted	2e , 2d , 2c	An average of 17% of labeled endothelial cells are found, usually prismatic or cubic. Staining density in mesenchymal cells in the proximal part was higher than in the distal part.

Structure	Level	Pattern	Image	Note
TS19: endocardial lining	Present	Regionally restricted		An average of 8% of labeled cells was present in the endocardium.

Structure	Level	Pattern	Image	Note
TS20: atrioventricular endocardial cushion	Present	Regionally restricted	3a	Most of the immunostained mesenchymal cells are situated near the endocardium.
TS20: left ventricle cardiac muscle	Present	Regionally restricted	3b , 3a , 3c	Expression was detected in cells in the compact layer of the anterior myocardial wall of the left ventricle. Staining was not seen in the posterior of the left ventricle.
TS20: interventricular septum	Absent		3a
TS20: right ventricle cardiac muscle	Absent		3a

Structure	Level	Pattern	Image	Note
TS20: heart left ventricle	Present	Regionally restricted	3d	Expression was detected in cells in the anterior wall of the left ventricle. Staining was not seen in the posterior of the left ventricle.
TS20: bulbar ridge	Present	Regionally restricted	3d	Expression was detected in the mesenchyme of the conotruncal ridges.
TS20: interventricular septum	Absent		3d
TS20: right ventricle cardiac muscle	Absent		3d

Structure	Level	Pattern	Image	Note
TS20: heart left ventricle	Present	Regionally restricted	3e , 3g	Expression was detected in cells in the anterior wall of the left ventricle. Staining was not seen in the posterior of the left ventricle.
TS20: bulbar ridge	Present	Regionally restricted	3e , 3f	Expression was detected in the mesenchyme of the conotruncal ridges. In the conotruncus, the repartition of positive cells seems regular, with possibly a higher proportion in the distal part.
TS20: interventricular septum	Absent		3e
TS20: right ventricle cardiac muscle	Absent		3e

Structure	Level	Pattern	Image	Note
TS20: bulbar ridge	Present	Regionally restricted	3h	Expression was detected in the mesenchyme of the conotruncal ridges.

Structure	Level	Pattern	Image	Note
TS21: left ventricle cardiac muscle	Present	Regionally restricted		In this section, staining was in a continuous strip at the level of the apex.

Structure	Level	Pattern	Image	Note
TS21: atrioventricular endocardial cushion	Present		4a
TS21: left ventricle cardiac muscle	Present	Regionally restricted	4a , 4b	Expression was in the anterior wall. In this section, it was in a discontinuous band at the largest width level of the ventricle, only in the compact layer.

Structure	Level	Pattern	Image	Note
TS21: atrioventricular endocardial cushion	Present	Regionally restricted	4c , 4d	Expression was in the mesenchyme.
TS21: bulbar ridge	Present	Regionally restricted	4c , 4d	Expression was in the mesenchyme.
TS21: left ventricle cardiac muscle	Present	Regionally restricted	4c , 4e	Expression was detected in the anterior and left lateral wall of the left ventricle. In this section, label was seen as a continuous strip of cells toward the top of the ventricle. Label was only in the compact layer.

Structure	Level	Pattern	Image	Note
TS21: left ventricle cardiac muscle	Present	Regionally restricted	4f	Expression was detected in the anterior and left lateral wall of the left ventricle. In this section, label was seen as a continuous strip of cells toward the top of the ventricle. Label was only in the compact layer.
TS21: bulbar ridge	Present	Regionally restricted	4f	Expression was in the mesenchyme of the conotrucal ridges.

Structure	Level	Pattern	Image	Note
TS21: bulbar ridge	Present	Regionally restricted	4g	Expression was in the mesenchyme of the conotruncal ridges.

Structure	Level	Pattern	Image	Note
TS21: aortic valve	Present		4h
TS21: pulmonary valve	Present		4h

Structure	Level	Pattern	Image	Note
TS22: left ventricle cardiac muscle	Present	Regionally restricted		Expression looked both continuous and discontinuous. Continuous at the level of the anterior wall. Discontinuous at the level of the lateral wall of the left ventricle. The thickness appeared variable.
TS22: aortic valve	Present	Single cells		Rare immunostained cells were observed.
TS22: pulmonary valve	Present	Single cells		Rare immunostained cells were observed.

Structure	Level	Pattern	Image	Note
TS23: left ventricle cardiac muscle	Present	Regionally restricted		The thickness of the labelled strip has decreased as well as its extension to the left.

Structure	Level	Pattern	Image	Note
TS25: interventricular septum	Present	Regionally restricted		Expression was in the endothelium of some vessels.

Structure	Level	Pattern	Image	Note
TS26: blood vessel endothelium	Present	Regionally restricted	5a , 5b	Expression was in the endothelium of some vessels.
TS26: interventricular septum	Present	Regionally restricted	5a , 5b	Expression was in the endothelium of some vessels.