Antibody:	Anti-Filamin-A
Detection system:	Secondary antibody coupled to Alexa Fluor 488

Structure	Level	Pattern	Image	Note
TS15: embryo	Present	Widespread	1B
TS15: branchial arch	Strong		1B
TS15: head	Present	Regionally restricted	1B	Expression was detected in developing facial prominences.
TS15: atrioventricular endocardial cushion	Present		1B
TS15: outflow tract endocardial cushion	Present		1B
TS15: proepicardium	Present		1B , 1C
TS15: visceral pericardium	Present		1B , 1C
TS15: cardiac muscle tissue	Absent		1C , 1B

Structure	Level	Pattern	Image	Note
TS15: branchial arch	Strong		1E
TS15: outflow tract endocardial cushion	Present		1E
TS15: cardiac muscle tissue	Absent		1E

Structure	Level	Pattern	Image	Note
TS15: atrioventricular endocardial cushion	Present		1F
TS15: cardiac muscle tissue	Absent		1F

Structure	Level	Pattern	Image	Note
TS19: superior atrioventricular endocardial cushion	Strong		2B
TS19: inferior atrioventricular endocardial cushion	Strong		2C , 2B
TS19: outflow tract endocardial cushion	Strong		2B
TS19: visceral pericardium	Strong		2B
TS19: heart endothelium	Strong	Regionally restricted	2B	Intense expression was detected in trabeculae endothelium.
TS19: blood vessel	Present		2B
TS19: atrioventricular sulcus	Present		2C , 2B
TS19: heart mesenchyme	Present	Regionally restricted	2C , 2B	Expression was detected in the mesenchymal cells of the atrioventricular and outflow tract cushion.
TS19: cardiac muscle tissue	Absent		2C , 2B

Structure	Level	Pattern	Image	Note
TS21: atrioventricular septal complex	Present		3B
TS21: atrioventricular sulcus	Present		3B
TS21: visceral pericardium	Present		3B
TS21: endocardial cushion	Present	Regionally restricted	3B , 3C	Expression was detected in the right and left lateral cushions. Expression was throughout both the endothelium and mesenchyme.
TS21: heart mesenchyme	Present	Regionally restricted	3B , 3C	Expression was detected in the mesenchyme of the left lateral cushion and the interstitial mesenchyme.
TS21: heart trabecula	Present	Regionally restricted	3C , 3B	Expression was detected in the ventricular trabeculae.

Structure	Level	Pattern	Image	Note
TS21: visceral pericardium	Strong		3E
TS21: heart septum	Strong	Regionally restricted	3F , 3E	Robust expression was detected in the developing conal septum.
TS21: ascending aorta	Weak		3E	Weak expression in the developing arterial wall.
TS21: cardiac muscle tissue	Absent		3F , 3E
TS21: endocardial cushion	Present	Regionally restricted	3E , 3F	Expression was detected in the mesenchyme of the fused conal cusion.

Structure	Level	Pattern	Image	Note
TS25: mitral valve	Strong		4B
TS25: tricuspid valve	Strong		4B
TS25: visceral pericardium	Strong		4B
TS25: cardiac interstitium	Present	Regionally restricted	4C , 4E , 4B	Expression was detected in non-myocytes within the myocardial interstitium.
TS25: atrioventricular sulcus	Present	Regionally restricted	4B , 4E , 4C	Expression was detected in the left and right atrioventricular sulcus.
TS25: trabeculae carneae	Present	Regionally restricted	4B , 4E	Expression was detected in the endothelium of the ventricular trabeculae.
TS25: aortic valve leaflet	Present	Regionally restricted	4D , 4B	Expression was most intense on the endothelial surface of the ventricular aspects of the valves, with weaker expression in the subendothelial mesenchyme/fibroblasts.
TS25: mitral valve leaflet	Present	Regionally restricted	4D , 4B	Expression was most intense on the endothelial surface of the ventricular aspects of the valves, with weaker expression in the subendothelial mesenchyme/fibroblasts.

Structure	Level	Pattern	Image	Note
TS25: descending aorta	Strong		5B , 5C
TS25: pulmonary vein	Strong		5B
TS25: aortic valve leaflet	Present	Graded	5B , 5C	A gradient of endothelial and subendothelial mesenchyme/fibroblast expression was noted with more intense staining on the endothelial surface. Expression was more robust on the ventricular aspect of the leaflets versus the arterial side.
TS25: visceral pericardium	Present		5B , 5D

Structure	Level	Pattern	Image	Note
TS28: aorta wall	Strong		6B
TS28: pulmonary artery	Strong		6B
TS28: aortic valve	Weak		6B
TS28: mitral valve	Weak		6B
TS28: tricuspid valve	Weak		6B
TS28: cardiac valve leaflet	Present	Graded	6B , 6D , 6C	Expression was graded from base to tip in mural mitral leaflet and the aortic leaflet of the mitral valve with higher levels detected in the base and mid regions of the leaflet. Additionally, subendothelial fibroblasts on the atrial aspect of the valve leaflets exhibit the highest level of expression. At this stage, very weak expression was detected in the ventricularis at the tips of the mitral leaflets.
TS28: heart anulus fibrosus	Present		6D , 6B
TS28: visceral pericardium	Present		6D , 6B
TS28: cardiac interstitium	Present		6B , 6E
TS28: heart blood vessel	Present		6B , 6E
TS28: cardiac muscle tissue	Absent		6E , 6B

Structure	Level	Pattern	Image	Note
TS28: aorta wall	Strong		7B
TS28: cardiac valve leaflet	Weak		7B , 7C	Expression was weak in the aortic and mitral leaflets.
TS28: heart anulus fibrosus	Weak	Regionally restricted	7D , 7B	Weak expression was detected in the annulus fibrosae. Fibroblasts intercalated at the annulus/myocardial border had the most intense staining.

Structure	Level	Pattern	Image	Note
TS28: heart blood vessel	Present	Regionally restricted	7E	Expression in the myocardial wall was restricted to the coronary vasculature.

Structure	Level	Pattern	Image	Note
TS28: cardiac valve leaflet	Present	Non-Uniform	8B	Expression was detected in the ventricularis endothelium of the adult mural mitral leaflet.
TS28: chordae tendinae	Present	Uniform	8C , 8B	Expression was detected in endothelial cells and fibroblasts.
TS28: heart papillary muscle	Absent		8B

Structure	Level	Pattern	Image	Note
TS19: outflow tract	Present	Regionally restricted	S1 (Fig. 9)C , S1 (Fig. 9)D , S1 (Fig. 9)G , S1 (Fig. 9)H	Expression was detected in all neural crest-derived cells in the outflow tract. Additional non-neural crest derived cells in the outlfow tract also stain positive (asterisks H).
TS19: mesenchyme derived from neural crest	Weak		S1 (Fig. 9)C , S1 (Fig. 9)D	Weak expression was detected in other neural crest-derived tissues.

Structure	Level	Pattern	Image	Note
TS19: atrioventricular endocardial cushion	Present		S2 (Fig. 10)G , S2 (Fig. 10)I , S2 (Fig. 10)D , S2 (Fig. 10)K , S2 (Fig. 10)C , S2 (Fig. 10)F	Expression was detected in the atrioventricular cushion mesenchyme and endothelium.
TS19: visceral pericardium	Present	Regionally restricted	S2 (Fig. 10)I , S2 (Fig. 10)D , S2 (Fig. 10)K , S2 (Fig. 10)C	Expression was detected in epicardial epithelium.
TS19: heart trabecula	Present	Regionally restricted	S2 (Fig. 10)D , S2 (Fig. 10)I , S2 (Fig. 10)C , S2 (Fig. 10)K	Expression was detected in the endothelium of the ventricular trabeculae.
TS19: atrioventricular sulcus	Present		S2 (Fig. 10)D , S2 (Fig. 10)I , S2 (Fig. 10)C , S2 (Fig. 10)K

Structure	Level	Pattern	Image	Note
TS23: atrioventricular septal complex	Present		S3 (Fig. 11)J , S3 (Fig. 11)L , S3 (Fig. 11)B , S3 (Fig. 11)D
TS23: atrioventricular valve	Present		S3 (Fig. 11)J , S3 (Fig. 11)L , S3 (Fig. 11)B , S3 (Fig. 11)D
TS23: visceral pericardium	Present		S3 (Fig. 11)H , S3 (Fig. 11)F , S3 (Fig. 11)B , S3 (Fig. 11)D
TS23: heart trabecula	Present	Regionally restricted	S3 (Fig. 11)H , S3 (Fig. 11)D , S3 (Fig. 11)B , S3 (Fig. 11)F	Expression was detected in the trabecular endothelium.
TS23: heart	Present	Regionally restricted	S3 (Fig. 11)L , S3 (Fig. 11)D , S3 (Fig. 11)H , S3 (Fig. 11)J , S3 (Fig. 11)F , S3 (Fig. 11)B	Expression was detected in myocardial interstitial cells.
TS23: heart left ventricle	Present	Regionally restricted	S3 (Fig. 11)H , S3 (Fig. 11)D , S3 (Fig. 11)F , S3 (Fig. 11)B	Expression was detected in epicardial derived cells in the left ventricle.
TS23: mitral valve	Present	Regionally restricted	S3 (Fig. 11)B , S3 (Fig. 11)H , S3 (Fig. 11)D , S3 (Fig. 11)F	Expression was detected in cells migrating into the mural mitral valve.