Figure 19.26

Origin of the Nervous

System

Process Diagrams Step-by-Step

Copyright © 2007 by John Wiley & Sons, Inc.

HEAD END

TAIL END

Neural plateNeural folds

Neural tube

Neural groove

Cut edge of amnion

1.

Neural plateEctoderm

Future neural crest

Notochord Endoderm

1.

Mesoderm

(a) Dorsal view

HEAD END

TAIL END

(a) Dorsal view

Neural plateNeural folds

Neural tube

Neural groove

Cut edge of amnion

2.

1.Neural folds

Neural grooveEndoderm

2.

Neural crestEctoderm

Somite

Notochord

Neural plateEctoderm

Future neural crest

Notochord Endoderm

1.

Mesoderm

HEAD END

TAIL END

Neural plateNeural folds

Neural tube

Neural groove

Cut edge of amnion

2.

1.

3.

Neural folds

Neural grooveEndoderm

2.

Neural crestEctoderm

Somite

Notochord

Neural tube

Notochord

Endoderm

(b) Transverse sections

3.

Neural crest

Ectoderm

Somite

Neural plateEctoderm

Future neural crest

Notochord Endoderm

1.

Mesoderm

(a) Dorsal view