Probe:	Shh probe88
Visualized with:	Alkaline phosphatase

Structure	Level	Pattern	Image	Note
TS16: hindgut epithelium	Present			Expression in hindgut endoderm, before initiation of paired genital swellings.

Structure	Level	Pattern	Image	Note
TS17: cloaca associated mesenchyme	Present	Regionally restricted	3A E10.5	Prior to onset of genital budding, expression throughout cloacal mesoderm.
TS17: genital swelling	Present	Regionally restricted	3A E10.5	As budding is initiated, expression persists throughout urethral endoderm.

Structure	Level	Pattern	Image	Note
TS19: urogenital sinus	Present	Regionally restricted	3A E11.5	Expression in endoderm of urogenital sinus, including urethral epithelium.

Structure	Level	Pattern	Image	Note
TS20: genital tubercle	Present	Regionally restricted	3A E12.5	Expression domain restricted to ventral side of genital tubercle, within urethral epithelium, contiguous between distal urethral plate and proximal urogenital sinus.
TS20: urethral plate	Present	Regionally restricted	3A E12.5	Expression domain restricted to ventral side of genital tubercle, within urethral epithelium, contiguous between distal urethral plate and proximal urogenital sinus.

Structure	Level	Pattern	Image	Note
TS21: genital tubercle	Present	Regionally restricted	3A E13.5	Expression domain displaced to ventral margin of tubercle.
TS21: preputial swelling	Present	Regionally restricted	3A E13.5	Focal expression on each of lateral preputial swellings.

Structure	Level	Pattern	Image	Note
TS22: epithelium of urogenital sinus	Present		3A E14.5	Expression in endoderm of urogenital sinus and derivatives, including urethral epithelium.
TS22: urethra	Present	Regionally restricted	3A E14.5	Expression domain narrowed within urethral plate of glans region; spreads proximally as plate opens to form lumen.
TS22: preputial swelling	Present	Regionally restricted	3A E14.5	Focal expression on each of lateral preputial swellings, within developing preputial glands.
TS22: preputial gland	Present		3A E14.5	Focal expression on each of lateral preputial swellings, within developing preputial glands.

Structure	Level	Pattern	Image	Note
TS20: genital tubercle	Present	Regionally restricted	4A	Expression in ventral midline of genital tubercle, restricted to ventral side of genital tubercle, contiguous between distal urethral plate and proximal urogenital sinus.
TS20: urethral plate	Present	Regionally restricted	4A	Expression in ventral midline of genital tubercle, restricted to ventral side of genital tubercle, contiguous between distal urethral plate and proximal urogenital sinus.
TS20: urogenital sinus	Present	Regionally restricted	4A	Expression in ventral midline of genital tubercle, restricted to ventral side of genital tubercle, contiguous between distal urethral plate and proximal urogenital sinus.

Structure	Level	Pattern	Image	Note
TS20: urethral plate	Present	Regionally restricted	4B	Expression within urethral epithelium, contiguous between distal urethral plate and proximal urogenital sinus.
TS20: urogenital sinus	Present	Regionally restricted	4B	Expression within urethral epithelium, contiguous between distal urethral plate and proximal urogenital sinus.

Structure	Level	Pattern	Image	Note
TS21: urethral plate	Present	Regionally restricted	4H	Expression throughout urethral epithelium. Expression domain narrowed with urethral plate of glans region, but spreads out proximally as plate opens to form lumen.
TS21: preputial gland	Present	Regionally restricted	4H	Focal expression on each of lateral preputial swellings, within developing preputial glands.
TS21: preputial swelling	Present	Regionally restricted	4H	Focal expression on each of lateral preputial swellings, within developing preputial glands.

Structure	Level	Pattern	Image	Note
TS21: epithelium of urogenital sinus	Present	Widespread	4I	Expression throughout urethral epithelium.
TS21: genital tubercle	Present	Regionally restricted	4I	Expression domain displaced to ventral margin of tubercle.