Antibody:	MEC 13.3
Detection system:	Secondary antibody

Structure	Level	Pattern	Image	Note
TS20: atrioventricular sulcus	Present		3E	A small number of positive nodules were normally found.

Structure	Level	Pattern	Image	Note
TS20: coronary vascular plexus	Present	Clusters	3F , 3H	Numerous ectopic positive nodules in the subepicardium, which were densely packed nucleated erythroid cells covered by a continuous epicardial layer.

Structure	Level	Pattern	Image	Note
TS20: coronary vascular plexus	Present		4G	Normal subepicardial vascular plexus covering ~90% of the left ventricle. Occasional nodular clusters of positive cells were seen.

Structure	Level	Pattern	Image	Note
TS20: coronary vascular plexus	Present		4H	Failed to develop a normal coronary plexus. Newly formed vessels were disorganized with fewer interconnections and more variable diameters in mutant hearts. Many more positive nodules were found scattered over the ventricular surface.

Structure	Level	Pattern	Image	Note
TS20: coronary vascular plexus	Present		4I	Failed to develop a normal coronary plexus. Newly formed vessels were disorganized with fewer interconnections and more variable diameters in mutant hearts. Many more positive nodules were found scattered over the ventricular surface.

Structure	Level	Pattern	Image	Note
TS20: coronary vascular plexus	Present		4J	Failed to develop a normal coronary plexus. Newly formed vessels were disorganized with fewer interconnections and more variable diameters in mutant hearts. Many more positive nodules were found scattered over the ventricular surface. Dense collections of unorganized positive cells were also occasionally found.

Structure	Level	Pattern	Image	Note
TS22: coronary artery	Present		5A	Two main coronary stems had formed in the correct locations.

Structure	Level	Pattern	Image	Note
TS22: coronary artery	Present		5B	Two main coronary stems had formed in the correct locations.

Structure	Level	Pattern	Image	Note
TS22: coronary artery	Present		5C	Vascular channels had begun to form in positions where the left coronary artery would later be found in mature hearts.

Structure	Level	Pattern	Image	Note
TS22: coronary artery	Present		5D	It was difficult to identify early coronary channels in the disorganized vascular plexus in the mutant.

Structure	Level	Pattern	Image	Note
TS24: left coronary artery	Present		5E

Structure	Level	Pattern	Image	Note
TS24: left coronary artery	Present		5F	Significant alterations in the pattern, and reductions in length and diameter of the left descending coronary artery in mutant hearts. Persistence of positive nodules was seen.