Antibody:	anti-Erbb3 (C17)
Detection system:	Biotinylated secondary antibody/[Strept]avidin coupled to horseradish peroxidase
Assay notes:	Embryos were fixed in 70% ethanol/1 % acetic acid.

Structure	Level	Pattern	Image	Note
TS19: gonadal mesenchyme	Weak	Regionally restricted	1a	Staining is weak in a few interstitial cells.

Structure	Level	Pattern	Image	Note
TS20: genital tubercle	Present		1b
TS20: gonadal mesenchyme	Present		1b

Structure	Level	Pattern	Image	Note
TS21: genital tubercle of male	Strong		1c	There are more cells expressing than there were at 12.5dpc.
TS21: testis	Strong		1c	There are more cells expressing than there were at 12.5dpc.

Structure	Level	Pattern	Image	Note
TS21: genital tubercle of male	Present	Regionally restricted	1d	There are fewer positive cells than there were at 13.0 dpc.
TS21: testis	Present	Regionally restricted	1d	There are fewer positive cells than there were at 13.0 dpc.

Structure	Level	Pattern	Image	Note
TS22: genital tubercle of male	Present	Regionally restricted	1e	Only a few cells are positive.
TS22: testis	Present	Regionally restricted	1e	Only a few cells are positive.

Structure	Level	Pattern	Image	Note
TS20: gonadal mesenchyme	Weak	Regionally restricted	1f	A few interstitial cells weakley express.

Structure	Level	Pattern	Image	Note
TS21: mesenchymal stroma of ovary	Weak	Regionally restricted	1g	A portion of interstitial cells weakly express.

Structure	Level	Pattern	Image	Note
TS22: mesenchymal stroma of ovary	Absent		1h	The authors note that there is no significant expression.