Probe:	Hcn4 cDNA
Probe preparation:	Antisense labelled with digoxigenin RNA
Visualized with:	Alkaline phosphatase
Assay notes:	Specimens were postfixed in 4% paraformaldehyde, 0.2% glutaraldehyde.

Structure	Level	Pattern	Image	Note
TS11: heart	Present	Single cells	1A	Expression is in the cardiac mesoderm.

Structure	Level	Pattern	Image	Note
TS12: sinus venosus	Present		1B	Symmetric expression, including the transverse middle portion.
TS12: sinus venosus left horn	Present		1B	Symmetric expression, including the transverse middle portion.
TS12: sinus venosus right horn	Present		1B	Symmetric expression, including the transverse middle portion.

Structure	Level	Pattern	Image	Note
TS12: sinus venosus	Present		1C	Symmetric expression, including the transverse middle portion.
TS12: sinus venosus left horn	Present		1C	Symmetric expression, including the transverse middle portion.
TS12: sinus venosus right horn	Present		1C	Symmetric expression, including the transverse middle portion.

Structure	Level	Pattern	Image	Note
TS12: sinus venosus	Present			Expression is at the junction between the common cardinal veins and the sinus venosus.
TS12: venous system	Present			Expression is at the junction between the common cardinal veins and the sinus venosus.

Structure	Level	Pattern	Image	Note
TS13: sinus venosus	Present		1D
TS13: common atrial chamber	Present	Regionally restricted	1D	There is a group of expressing cells in the left atrium.

Structure	Level	Pattern	Image	Note
TS13: sinus venosus	Present		1E
TS13: common atrial chamber	Present	Regionally restricted	1E	There is a group of expressing cells in the left atrium.

Structure	Level	Pattern	Image	Note
TS13: sinus venosus	Present		1F
TS13: common atrial chamber	Present	Regionally restricted	1F	There is a group of expressing cells in the left atrium.

Structure	Level	Pattern	Image	Note
TS14: septum transversum	Present		1G
TS14: sinus venosus right horn	Present		1G

Structure	Level	Pattern	Image	Note
TS14: septum transversum	Present		1H
TS14: sinus venosus left horn	Present		1H

Structure	Level	Pattern	Image	Note
TS14: septum transversum	Present		1I
TS14: sinus venosus left horn	Present		1I

Structure	Level	Pattern	Image	Note
TS13: common atrial chamber	Present	Regionally restricted	1J	Expression is in the left atrial wall.

Structure	Level	Pattern	Image	Note
TS13: common atrial chamber	Present	Regionally restricted	1K	Expression is in the left atrial wall.

Structure	Level	Pattern	Image	Note
TS13: common atrial chamber	Present	Regionally restricted	1L	Expression is in the left atrial wall.

Structure	Level	Pattern	Image	Note
TS13: common atrial chamber	Present	Regionally restricted	1M	Expression is in the left atrial wall.

Structure	Level	Pattern	Image	Note
TS16: heart	Present		2A
TS16: sinus venosus	Present		2A
TS16: future brain	Present	Regionally restricted	2A	Expression is in the proliferating neuroepithelia lining the brain ventricles.

Structure	Level	Pattern	Image	Note
TS16: heart	Present		2B
TS16: sinus venosus	Present		2B
TS16: future brain	Present	Regionally restricted	2B	Expression is in the proliferating neuroepithelia lining the brain ventricles.

Structure	Level	Pattern	Image	Note
TS16: common atrial chamber right part	Present	Regionally restricted	2C	Expression is in the dorsal part of the right wall.
TS16: sinus venosus right horn	Present		2C

Structure	Level	Pattern	Image	Note
TS16: septum transversum	Strong		2D
TS16: sinus venosus left horn	Present		2D

Structure	Level	Pattern	Image	Note
TS16: common atrial chamber right part	Present	Regionally restricted	2E	There is asymmetric expression in the dorsal wall of the right atrium.
TS16: sinus venosus right horn	Present	Regionally restricted	2E	Expression is in the rostral portion.

Structure	Level	Pattern	Image	Note
TS16: common atrial chamber right part	Present	Regionally restricted	2F	There is asymmetric expression in the dorsal wall of the right atrium.
TS16: sinus venosus right horn	Present	Regionally restricted	2F	Expression is in the rostral portion.

Structure	Level	Pattern	Image	Note
TS16: heart	Present	Regionally restricted	2G	There is asymmetric expression in the right side, at the junction between the common cardinal vein and the sinus venosus.
TS16: septum transversum	Present		2G

Structure	Level	Pattern	Image	Note
TS16: heart	Present	Regionally restricted	2H	There is asymmetric expression in the right side, at the junction between the common cardinal vein and the sinus venosus.
TS16: septum transversum	Present		2H

Structure	Level	Pattern	Image	Note
TS16: future hindbrain	Strong
TS16: future hindbrain roof plate	Strong
TS16: diencephalon	Present		2I
TS16: optic cup	Present		2I
TS16: optic stalk	Present		2I
TS16: telencephalon	Present		2I

Structure	Level	Pattern	Image	Note
TS16: future midbrain	Weak

Structure	Level	Pattern	Image	Note
TS20: right atrium	Present	Regionally restricted	3A	This is a frontal view of the whole heart where no expression is seen. The dorsal view (3B) of the heart shows asymmetrical expression in the dorsal wall of the right atrium.

Structure	Level	Pattern	Image	Note
TS20: right atrium	Present	Regionally restricted	3B	Asymmetrical expression in the dorsal wall of the right atrium.
TS20: venous system	Present	Regionally restricted	3B	Expression is in the coronary sinus extending to the left atria.
TS20: common cardinal vein	Present		3B
TS20: sinus venosus left horn	Weak		3B

Structure	Level	Pattern	Image	Note
TS20: common cardinal vein	Strong	Regionally restricted	3C	Expression is surrounding the orifice of the right common cardinal vein.
TS20: right atrium	Strong	Regionally restricted	3C	Expression is in the dorsal wall.
TS20: sinus venosus left horn	Weak		3C

Structure	Level	Pattern	Image	Note
TS20: common cardinal vein	Present	Regionally restricted	3D	Expression is in the junction between the right common cardinal vein and the right atrial appendage. Some expression is in the left common cardinal vein.
TS20: right atrium	Present	Regionally restricted	3D	Expression is in the junction between the right common cardinal vein and the right atrial appendage. Some expression is in the left common cardinal vein.
TS20: sinus venosus left horn	Weak		3D

Structure	Level	Pattern	Image	Note
TS20: common cardinal vein	Present	Regionally restricted	3E	Expression is at the junction between the right atrium and the common cardinal vein.
TS20: right atrium	Present	Regionally restricted	3E	Expression is at the junction between the right atrium and the common cardinal vein.
TS20: sinus venosus left horn	Present		3E

Structure	Level	Pattern	Image	Note
TS28: heart	Strong	Regionally restricted	4A	Expression is surrounding the portion of the superior vena cava in close proximity to the right atrial appendage.
TS28: sinoatrial node	Strong		4A

Structure	Level	Pattern	Image	Note
TS28: right atrium	Strong	Regionally restricted	4B	Expressing cells occupy the junction between the superior vena cava and the right atrial appendage.
TS28: sinoatrial node	Strong	Regionally restricted	4B	Expressing cells occupy the junction between the superior vena cava and the right atrial appendage.

Structure	Level	Pattern	Image	Note
TS28: vena cava	Strong	Regionally restricted	4C	Expression is between the orifices of the superior and inferior vena cava.
TS28: right atrium	Strong	Regionally restricted	4C	Expression is in the dorsal wall of the right atrium.
TS28: sinoatrial node	Strong		4C

Structure	Level	Pattern	Image	Note
TS28: right atrium	Strong	Regionally restricted	4D	Expression is at the in the junction between the superior vena cava and the right atrial appendage.
TS28: vena cava	Strong	Regionally restricted	4D	Expression is at the in the junction between the superior vena cava and the right atrial appendage.
TS28: sinoatrial node	Strong		4D

Structure	Level	Pattern	Image	Note
TS28: right atrium	Present	Regionally restricted	5A	Expression is at the junction between the superior vena cava and the right atrial appendage.
TS28: sinoatrial node	Present		5A

Structure	Level	Pattern	Image	Note
TS28: right atrium	Present	Regionally restricted	5B	Expressing cells are surrounding the orifice of the superior vena cava, and extending caudally, following the crista terminalis as a border.
TS28: sinoatrial node	Present		5B

Structure	Level	Pattern	Image	Note
TS28: right atrium	Present	Regionally restricted	5C	Expressing cells are located surrounding the superior vena cava at the junction with the right atrial appendage.
TS28: sinoatrial node	Present		5C