Antibody:	Gax8.1 antibody
Detection system:	Biotinylated secondary antibody/[Strept]avidin coupled to horseradish peroxidase

Structure	Level	Pattern	Image	Note
TS11: lateral plate mesoderm	Present
TS11: intraembryonic coelom	Absent			No expression in cells surrounding the intraembryonic coelomic cavity, which becomes the pericardial cavity.

Structure	Level	Pattern	Image	Note
TS12: primitive heart tube	Present	Widespread	2A	Expression in most cardiomyocytes of early heart tube.
TS12: neural plate	Present		2A	Expression in the central nervous system.

Structure	Level	Pattern	Image	Note
TS20: compact myocardium	Present		2C	Peak expression by day 12.5 to 13.0 in the atrium and in the trabeculae and developing compact layer of the ventricles.
TS20: heart atrium	Present		2C	Peak expression by day 12.5 to 13.0 in the atrium and in the trabeculae and developing compact layer of the ventricles.
TS20: trabecular myocardium	Present		2C	Peak expression by day 12.5 to 13.0 in the atrium and in the trabeculae and developing compact layer of the ventricles.

Structure	Level	Pattern	Image	Note
TS20: mesenchyme of metanephros	Present	Regionally restricted		Expression within mesenchyme surrouding tubules and glomeruli of kidney, in a pattern consistent with mesangial and juxtraglomerular cells, which have contractile and proliferative properties similar to smooth muscle cells.

Structure	Level	Pattern	Image	Note
TS21: compact myocardium	Present	Regionally restricted	2D	Peak expression by day 12.5 to 13.0 in the atrium and in the trabeculae and developing compact layer of the ventricles.
TS21: heart atrium	Present	Regionally restricted	2D	Peak expression by day 12.5 to 13.0 in the atrium and in the trabeculae and developing compact layer of the ventricles.
TS21: trabecular myocardium	Present	Regionally restricted	2D	Peak expression by day 12.5 to 13.0 in the atrium and in the trabeculae and developing compact layer of the ventricles.

Structure	Level	Pattern	Image	Note
TS21: heart	Absent			Authors report that expression was undetectable by immunohistochemistry by day 13.5.

Structure	Level	Pattern	Image	Note
TS23: compact myocardium	Present		2E	Expression again readily detectable by day 15.5 in nuclei of some cells in the compact layer of the ventricle.
TS23: pharynx muscularis	Present	Regionally restricted	2E	Expression in visceral smooth muscle of posterior pharynx.
TS23: diaphragm	Present		2E
TS23: thymus primordium	Present	Regionally restricted	2E	Expression in vasculature of several organs including the thymus.

Structure	Level	Pattern	Image	Note
TS23: compact myocardium	Present	Regionally restricted	2F	Expression again readily detectable by day 15.5 in nuclei of some cells in the compact layer of the ventricle.

Structure	Level	Pattern	Image	Note
TS23: bladder	Present	Regionally restricted		Expression in visceral smooth muscle of the bladder.

Structure	Level	Pattern	Image	Note
TS12: primitive heart tube cardiac muscle	Present	Regionally restricted	3D	Predominantly cytoplasmic/perinuclear expression in myocardium.

Structure	Level	Pattern	Image	Note
TS23: compact myocardium	Present	Regionally restricted	3F	Marked nuclear expression within compact layer of ventricle.

Structure	Level	Pattern	Image	Note
TS25: ventricle cardiac muscle	Present			Authors report expression pattern within ventricular myocardium persisted through day 17.5.

Structure	Level	Pattern	Image	Note
TS15: hindgut	Present		4A

Structure	Level	Pattern	Image	Note
TS20: stomach	Present	Regionally restricted	4B	Expression clearly apparent in two layers of stomach: a well-defined inner (submucosal) and a more diffuse external layer, extending from stomach to distal intestine.

Structure	Level	Pattern	Image	Note
TS23: stomach	Present	Regionally restricted	4C	Expression more discretedly organized. Expresion in stomach delineates two clearly distinct layers: the muscularis submucosa and muscularis externa.
TS23: stomach muscularis externa	Present		4C

Structure	Level	Pattern	Image	Note
TS23: stomach	Present	Regionally restricted	4D	Predominantly nuclear expression in muscularis submucosa.
TS23: stomach muscularis externa	Present	Diffuse	4D

Structure	Level	Pattern	Image	Note
TS12: somite	Present		5A	Expression detected in the first somites around day 8.0.
TS12: neural ectoderm	Present		5A	Expression in the central nervous system.

Structure	Level	Pattern	Image	Note
TS13: somite	Present		5B	Expression in somitic cells, intensified with mesodermal condensation.

Structure	Level	Pattern	Image	Note
TS14: dermomyotome	Strong	Uniform	5C
TS14: sclerotome	Strong	Uniform	5C

Structure	Level	Pattern	Image	Note
TS15: trunk somite	Strong	Regionally restricted	5D	Expression remained high during migration of cells from somites into the trunk.

Structure	Level	Pattern	Image	Note
TS19: trunk musculature	Present	Regionally restricted	5E	Expression in myoblasts surrounding early chondrification centers of ribs and vertebrae.

Structure	Level	Pattern	Image	Note
TS15: trunk somite	Present	Regionally restricted	5F	Expression in premyogenic cells from lateral somites migrating into the limb bud.

Structure	Level	Pattern	Image	Note
TS20: limb mesenchyme	Present	Regionally restricted	6A	Expression at periphery of limb buds.

Structure	Level	Pattern	Image	Note
TS21: limb mesenchyme	Present	Regionally restricted	6B	Expression at periphery of limb buds.

Structure	Level	Pattern	Image	Note
TS15: branchial arch	Present

Structure	Level	Pattern	Image	Note
TS17: inner ear	Present	Regionally restricted	6D	Expression in the cochlea.
TS17: eye mesenchyme	Present	Regionally restricted	6D	Expression in extraocular muscles.
TS17: head mesenchyme	Present	Regionally restricted	6D	Expression in other skeletal muscles of the head.

Structure	Level	Pattern	Image	Note
TS23: olfactory epithelium	Present		6E
TS23: tongue	Present		6E
TS23: vibrissa	Strong	Regionally restricted	6E	High levels of expression in region surrounding, but not within, whisker follicles.

Structure	Level	Pattern	Image	Note
TS23: esophagus muscularis	Present	Regionally restricted	6F	Expression in visceral smooth muscle of proximal portion of esophagus.

Structure	Level	Pattern	Image	Note
TS23: facial muscle	Present	Regionally restricted	6G	Expression in external facial muscles.
TS23: vibrissa	Strong	Regionally restricted	6G	High levels of expression in region surrounding, but not within, whisker follicles.
TS23: retina	Present		6G