front matter 1

Retreating

roof plate

Dorsal median septum

Ventral median fissure

Floor plateFloor plate

Persisting

central

canal

Ventral horn

interneurons

Ventral horn

interneurons

Intermediate

interneurons

Intermediate

interneurons

Retreating roof plate

Floor plate

Dorsal root ganglion

Dorsal root

Dorsal root

Surrounding

meningeal

membranes

Expanding gray matter

Expanding white matter

Ependyma

Persisting central canal

Dorsal root bifurcation zone

Fasciculus cuneatus

Fasciculus gracilis?

Dorsal root collateralization zone

Lissauer's tract?

Dorsal funiculus

Dorsal hornDorsal horn

Substantia

gelatinosa

Substantia

gelatinosa

EpendymaEpendyma

Receding dorsal

neuroepithelium

Receding dorsal

neuroepithelium

Receding dorsal

neuroepithelium

Central

autonomic

area

Central

autonomic

area

Lateral

cervical

nucleus

Lateral

cervical

nucleus

Lamina ILamina I

Laminae

IV-V

Laminae

IV-V

Segregating ventral horn

motoneuron columns

Segregating ventral horn

motoneuron columns

distal

upper limb

motoneurons

distal

upper limb

motoneurons

proximal

upper limb

motoneurons

proximal

upper limb

motoneurons

axial

motoneurons

axial

motoneurons

Ventral

white commissure

Ventral

white commissure

V

e

nt

ral

funiculus

V

e

nt

ral

funiculus

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

Large arrows extending from the neuroepithelium indicate migrating neurons.

Small arrow in the spinal canal indicates the direction of contraction.

PLATE 12B