Antibody:	anti-periostin
Detection system:	fluorescein

Structure	Level	Pattern	Image	Note
TS15: atrioventricular canal	Present		1A	Onset of expression in atrioventricular canal.
TS15: atrioventricular canal cardiac muscle	Absent		1A
TS15: umbilical blood vessel	Strong		1A

Structure	Level	Pattern	Image	Note
TS15: atrioventricular canal	Present	Regionally restricted	1B	Authors report subendocardial expression in atrioventricular canal.
TS15: atrioventricular endocardial cushion	Present	Regionally restricted	1B	Cytoplasmic expression in transformed mesenchymal cells of forming atrioventricular cushion.

Structure	Level	Pattern	Image	Note
TS18: atrioventricular endocardial cushion	Present	Regionally restricted	1C	Expression in atrioventricular and outflow tract cushion mesenchyme.
TS18: outflow tract endocardial cushion	Present	Regionally restricted	1C	Expression in atrioventricular and outflow tract cushion mesenchyme.

Structure	Level	Pattern	Image	Note
TS18: atrioventricular endocardial cushion	Strong	Regionally restricted	1D	Intense expression in atrioventricular and outflow tract cushion mesenchyme.
TS18: outflow tract endocardial cushion	Strong	Regionally restricted	1D	Intense expression in atrioventricular and outflow tract cushion mesenchyme.

Structure	Level	Pattern	Image	Note
TS20: endocardial cushion	Strong	Regionally restricted	1E	Intense expression in outflow tract cushion.
TS20: outflow tract	Present	Regionally restricted	1E	Authors state expression extends beyond border of outflow tract covered by myocardium.
TS20: visceral pericardium	Present		1E	Expression in the epicardium.

Structure	Level	Pattern	Image	Note
TS20: atrioventricular endocardial cushion	Strong		1F
TS20: visceral pericardium	Present		1F	Expression within epicardium.
TS20: ventricle endocardial lining	Present	Regionally restricted	1F	Expression within endothelial lining of ventricular trabeculae.

Structure	Level	Pattern	Image	Note
TS21: aortic valve	Strong	Widespread	2A
TS21: dorsal aorta	Weak		2A	Authors report weak expression within the aorta.
TS21: atrioventricular endocardial cushion	Weak	Regionally restricted	2A	Weak expression within anterior aspect of the interventricular septum, representing ventral mesenchyme of fused atrioventricular cushion.
TS21: interventricular septum	Weak	Regionally restricted	2A	Weak expression within anterior aspect of the interventricular septum, representing ventral mesenchyme of fused atrioventricular cushion.

Structure	Level	Pattern	Image	Note
TS21: mitral valve	Strong	Regionally restricted	2B	Intense expression in developing tricuspid and mitral valves - predominantly localized to atrial aspect of each valve.
TS21: tricuspid valve	Strong	Regionally restricted	2B	Intense expression in developing tricuspid and mitral valves - predominantly localized to atrial aspect of each valve.
TS21: interatrial septum	Strong	Regionally restricted	2B	Intense expression in mesenchymal cap of dorsal mesenchymal protrusion - part of atrial septum that attaches to the fused atrioventricular cusion.

Structure	Level	Pattern	Image	Note
TS21: interatrial septum	Present	Regionally restricted	2C	Authors report fibrous expression in tricuspid valve, mitral valve and dorsal mesenchymal protrusion.
TS21: mitral valve	Present	Regionally restricted	2C	Authors report fibrous expression in tricuspid valve, mitral valve and dorsal mesenchymal protrusion.
TS21: tricuspid valve	Present	Regionally restricted	2C	Authors report fibrous expression in tricuspid valve, mitral valve and dorsal mesenchymal protrusion.

Structure	Level	Pattern	Image	Note
TS21: visceral pericardium	Present	Regionally restricted	2D	Expression within forming epicardium covering ventricle and atrium.
TS21: ventricle endocardial lining	Present	Regionally restricted	2D	Expression in endothelial lining of ventricular trabeculae.

Structure	Level	Pattern	Image	Note
TS24: pulmonary valve	Strong	Regionally restricted	2E	Intense expression in forming pulmonary valves - more intense expression on ventricular aspect of leaflet.
TS24: aorta	Strong		2E
TS24: pulmonary trunk	Strong		2E

Structure	Level	Pattern	Image	Note
TS24: tricuspid valve	Present		2F
TS24: visceral pericardium	Present		2F

Structure	Level	Pattern	Image	Note
TS24: mitral valve	Strong		2G
TS24: interventricular septum	Present	Regionally restricted	2G	Expression near luminal edge of interventricular septum.
TS24: impulse conducting system	Present	Regionally restricted	2G	Strands of expression associated with fibrous components of the developing conduction system.

Structure	Level	Pattern	Image	Note
TS24: cardiac muscle tissue	Present	Regionally restricted	2H	Authors report robust expression in epicardial derived cells in the myocardial wall.``

Structure	Level	Pattern	Image	Note
TS28: aorta	Strong		2I
TS28: aortic valve	Strong		2I
TS28: aorta wall	Present	Regionally restricted	2I	Authors report fibrous expression in the aortic wall.

Structure	Level	Pattern	Image	Note
TS28: chordae tendinae	Strong		2J	Intense expression in tendinous chord, attached to papillary muscle.

Structure	Level	Pattern	Image	Note
TS28: tricuspid valve	Strong		2K

Structure	Level	Pattern	Image	Note
TS28: mitral valve	Strong		2L