front matter 1

Postulated sojourn zone

of premigratory neurons

in the dorsal neuroepithelium

Postulated sojourn zone

of premigratory neurons

in the dorsal neuroepithelium

Floor plateFloor plate

Central

canal

Ventral horn

interneurons

Ventral horn

interneurons

Intermediate

interneurons

Intermediate

interneurons

Dorsal

root

Dorsal root

bifurcation zone

Fasciculus cuneatus

Dorsal root

collateralization zone

Lissauer's

tract?

Dorsal funiculus

Dorsal horn

Substantia

gelatinosa

Substantia

gelatinosa

EpendymaEpendyma

Central

autonomic

area

Central

autonomic

area

Lateral

cervical

nucleus

Lateral

cervical

nucleus

Lamina ILamina I

Central

cervical

nucleus?

Central

cervical

nucleus?

Migrating

lateral cervical

nucleus neurons?

Migrating

lateral cervical

nucleus neurons?

Dorsal neuroepithelium

Laminae

IV-V

Laminae

IV-V

Dorsal

canal

Dorsal

canal

Segregating ventral horn

motoneuron columns

Segregating ventral horn

motoneuron columns

axial

motoneurons

axial

motoneurons

digit and hand

motoneurons

digit and hand

motoneurons

forearm,

arm, and

shoulder

motoneurons

forearm,

arm, and

shoulder

motoneurons

Retreating roof plate

Ventral

white

commissure

Ventral

white

commissure

Ventral

median fissure

Ventral

median fissure

Ventral gray

commissure

Ventral gray

commissure

Dorsal median septum

Dorsal intermediate septum

Fasciculus gracilis?

V e n t r a l

f u n i c u l

u

s

V e n t r a l

f u n i c u l

u

s

L a t e r a l f u n i c u l u s

L a t e r a l f u n i c u l u s

PLATE 15B