Probe:	Sek-2 cDNA1
Probe preparation:	Antisense labelled with digoxigenin RNA
Visualized with:	Alkaline phosphatase

Structure	Level	Pattern	Image	Note
TS11: primitive streak	Present		3A
TS11: node	Present		3A	Highest levels were present in the node.

Structure	Level	Pattern	Image	Note
TS11: primitive streak	Present		3B
TS11: node	Present		3B	Highest levels were present in the node.

Structure	Level	Pattern	Image	Note
TS11: primitive streak	Present	Regionally restricted		Expression was detected in the anterior part of the primitive streak.

Structure	Level	Pattern	Image	Note
TS11: embryo	Present	Regionally restricted	3E	Expression was detected in a band of more anterior cells within the primitive headfold.

Structure	Level	Pattern	Image	Note
TS12: future spinal cord neural plate	Strong	Uniform	3F	Expression was continuous throughout the neural plate.
TS12: neural plate	Strong		3F
TS12: embryo mesenchyme	Present	Regionally restricted	3F	Expression was in the mesoderm adjacent to the neural plate.

Structure	Level	Pattern	Image	Note
TS12: future spinal cord neural plate	Present		3G	Expression starts to decrease in the medial region of the neural plate around the 3-somite stage.

Structure	Level	Pattern	Image	Note
TS12: neural plate	Present		3H	Expression in the floor plate starts to decrease.
TS12: neural fold	Present		3H
TS12: embryo mesenchyme	Present	Regionally restricted	3H	Expression persists in the mesoderm adjacent to the neural plate.

Structure	Level	Pattern	Image	Note
TS12: neural fold	Present		3I
TS12: embryo mesenchyme	Present	Regionally restricted	3I	Expression persists in the mesoderm adjacent to the neural plate.

Structure	Level	Pattern	Image	Note
TS12: future spinal cord neural plate	Present	Regionally restricted	3J	Expression was downregulated in the medial region of the neural plate.
TS12: neural plate	Present	Regionally restricted	3J	Expression was downregulated in the floor plate.
TS12: surface ectoderm	Present		3J
TS12: neural fold	Present	Regionally restricted	3J	Expression was detected in the lateral neural folds.
TS12: embryo mesenchyme	Present	Regionally restricted	3J	Expression was detected in the lateral mesoderm.

Structure	Level	Pattern	Image	Note
TS13: head mesenchyme	Present	Regionally restricted	3N	Expression was detected in mesenchymal cells localized posterior to Hoxb1 expression in rhombomere 4 and separate from neural crest cells adjacent to rhombomere 4.

Structure	Level	Pattern	Image	Note
TS14: future hindbrain	Absent		3O
TS14: head mesenchyme	Present	Regionally restricted	3O	Expression was detected in the mesenchyme adjacent to the hindbrain and surrounding the otic vesicle.

Structure	Level	Pattern	Image	Note
TS14: embryo ectoderm	Absent			The ectoderm adjacent to the otic vesicle was not labeled.

Structure	Level	Pattern	Image	Note
TS14: future hindbrain	Absent		3P
TS14: head mesenchyme	Present	Regionally restricted	3P	Expression was detected in the cells, which may include neural crest cells, next to the posterior half of the otic vesicle in a domain which extends ventrally next to rhombomere 6.

Structure	Level	Pattern	Image	Note
TS15: future hindbrain	Absent		3Q
TS15: head mesenchyme	Present	Regionally restricted	3Q	Expression was detected in the mesenchyme adjacent to the hindbrain and surrounding the otic vesicle.
TS15: 3rd branchial arch	Present		3Q