Probe:	Sek-3
Probe preparation:	Antisense labelled with digoxigenin RNA
Visualized with:	Alkaline phosphatase

Structure	Level	Pattern	Image	Note
TS11: embryo	Present	Regionally restricted		Expression was detected in the anterior half of the embryo.

Structure	Level	Pattern	Image	Note
TS12: neural ectoderm	Present	Regionally restricted	4G	Expression was detected in the anterior half of the neuroectoderm.
TS12: embryo	Present	Regionally restricted	4G	Expression was detected in the posterior tip of the embryo.

Structure	Level	Pattern	Image	Note
TS13: rhombomere 2	Present	Regionally restricted	4H	Expression was detected in the ventral part of rhombomere 2.
TS13: rhombomere 3	Present	Widespread	4H	Expression was detected throughout rhombomeres 3 and 5.
TS13: rhombomere 5	Present	Widespread	4H	Expression was detected throughout rhombomeres 3 and 5.
TS13: future midbrain	Strong	Regionally restricted	4H	Expression was detected in ventral midbrain.

Structure	Level	Pattern	Image	Note
TS13: rhombomere 2	Present	Regionally restricted	4I	Expression was detected in the ventral part of rhombomere 2.
TS13: rhombomere 3	Present	Widespread	4I	Expression was detected throughout rhombomeres 3 and 5.
TS13: rhombomere 5	Present	Widespread	4I	Expression was detected throughout rhombomeres 3 and 5.
TS13: future midbrain	Strong	Regionally restricted	4I	Expression was strong in the ventral midbrain.
TS13: future prosencephalon	Strong	Regionally restricted	4I	Expression was strong in the ventroposterior forebrain, with a lower level extending more anteriorly.
TS13: head mesenchyme	Present	Regionally restricted	4I	Expression was detected in the lateral mesoderm of the head and trunk.
TS13: trunk mesenchyme	Present	Regionally restricted	4I	Expression was detected in the lateral mesoderm of the head and trunk.

Structure	Level	Pattern	Image	Note
TS13: rhombomere 2	Present		5B
TS13: rhombomere 3	Present		5B
TS13: rhombomere 5	Present		5B
TS13: future midbrain	Present	Regionally restricted	5B	Expression was detected in the ventral midbrain.
TS13: future prosencephalon	Present	Regionally restricted	5B	Expression was detected in the diencephalon.
TS13: optic pit	Present	Regionally restricted	5B	Expression was detected in the posterior part of the optic vesicle.
TS13: foregut diverticulum	Weak	Regionally restricted	5B	Low level expression was detected in the lining of the posterior half of the foregut pocket.
TS13: trunk mesenchyme	Weak	Regionally restricted	5B	Low level expression was detected in the mesoderm immediately posterior to the heart.

Structure	Level	Pattern	Image	Note
TS14: future hindbrain	Weak		5E	Expression was downregulated in the hindbrain.
TS14: rhombomere 5	Trace		5E
TS14: future midbrain	Present	Regionally restricted	5E	Expression was detected in the ventral midbrain.
TS14: future diencephalon	Present	Regionally restricted	5E	Expression was detected in the ventral diencephalon.
TS14: prosencephalon	Present	Regionally restricted	5E	Expression was detected in the posterior ventral part of the telencephalon.
TS14: optic vesicle	Present	Regionally restricted	5E	Expression was detected in the posterior ventral part of the optic vesicle.

Structure	Level	Pattern	Image	Note
TS15: future midbrain	Present	Regionally restricted	5H	Expression was detected in the ventral midbrain.
TS15: diencephalon	Present	Regionally restricted	5H	Expression was detected in the ventral diencephalon.
TS15: telencephalon	Present	Regionally restricted	5H	Expression was detected in the posterior ventral part of the telencephalon.
TS15: optic vesicle	Present	Regionally restricted	5H	Expression was detected in the posterior ventral part of the optic vesicle.
TS15: dorsal root ganglion	Weak		5H

Structure	Level	Pattern	Image	Note
TS15: future midbrain	Present	Regionally restricted	5I	Expression was detected in the ventral midbrain.
TS15: diencephalon	Present	Regionally restricted	5I	Expression was detected in the ventral diencephalon.
TS15: telencephalon	Present	Regionally restricted	5I	Expression was detected in the posterior ventral part of the telencephalon.
TS15: optic vesicle	Present	Regionally restricted	5I	Expression was detected in the posterior ventral part of the optic vesicle.

Structure	Level	Pattern	Image	Note
TS15: future midbrain	Strong	Regionally restricted	5I inset	The high level expression in the midbrain is anterior to the midbrain-hindbrain boundary defined by Wnt1 expression, but expression overlaps with Wnt1 in the ventral midbrain.
TS15: central nervous system	Weak	Widespread	5I inset	A low level expression was observed throughout the central nervous system.

Structure	Level	Pattern	Image	Note
TS17: dorsal root ganglion	Present