Antibody:	CRTL1 (HPLN1) antibody
Detection system:	Alexa Fluor 488

Structure	Level	Pattern	Image	Note
TS15: atrioventricular endocardial cushion	Present	Regionally restricted	2A	Expression in extracellular matrix surrounding endocardial and endocardial-derived cells of the atrioventricular cushion mesenchyme.

Structure	Level	Pattern	Image	Note
TS15: atrioventricular endocardial cushion	Present	Regionally restricted	2C	Expression in extracellular matrix surrounding endocardial and endocardial-derived cells of the atrioventricular cushion mesenchyme.
TS15: atrium endocardial lining	Present		2C
TS15: primitive ventricle endocardial lining	Present		2C
TS15: dorsal mesocardium	Strong	Regionally restricted	2C	Strong expression in the reflections of the dorsal mesocardium.

Structure	Level	Pattern	Image	Note
TS15: primitive ventricle endocardial lining	Present		2D

Structure	Level	Pattern	Image	Note
TS15: primitive ventricle endocardial lining	Present		2F

Structure	Level	Pattern	Image	Note
TS17: outflow tract endocardial cushion	Strong	Regionally restricted	2G	Abundant expression in sub-endocardial matrix of conal cushions in proximal outflow tract.
TS17: truncus arteriosus	Weak	Regionally restricted	2G	Little expression in sub-endocardial mesenchyme of truncal outflow tract ridges.

Structure	Level	Pattern	Image	Note
TS17: atrioventricular endocardial cushion	Present		2H	Authors report high degree of co-expression with versican in atrioventricular cushions.`

Structure	Level	Pattern	Image	Note
TS21: outflow tract	Strong	Regionally restricted	3A	Strong expression in most proximal portion of outflow tract mesenchyme (conal cushions). No expression in proximal truncal ridges.
TS21: semilunar valve	Strong	Regionally restricted	3A	Strong expression in distal-most part of truncal endocardial ridges (upper boundary of developing semilunar valves).

Structure	Level	Pattern	Image	Note
TS21: inferior atrioventricular endocardial cushion	Present		3E	Authors report expression restricted to atrioventricular mesenchymal structures that are of endocardial origin - inferior, superior and lateral atrioventricular cushions.
TS21: heart mesenchyme	Present	Regionally restricted	3E	Strong expression in distal-most part of truncal endocardial ridges (upper boundary of developing semilunar valves).

Structure	Level	Pattern	Image	Note
TS22: tricuspid valve	Strong		4C , 4A	Authors report overlapping expression with versican in leaflets of tricuspid valve. Higher expression in tricuspid valve leaflets compared to leaflets of mitral valve.
TS22: mitral valve	Present		4A , 4C	Authors report overlapping expression with versican in leaflets of mitral atrioventricular valve.