front matter 1

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

Cellular roof plate

Fibrous roof plate

Floor plateFloor plate

Dorsal

canal

Dorsal

canal

Central canalCentral canal

Receding

ventral canal

Receding

ventral canal

Segregating

ventral horn

motoneurons

Segregating

ventral horn

motoneurons

Settling

ventral horn

interneurons

Settling

ventral horn

interneurons

Migrating and settling

dorsal horn neurons

Intermediate

interneurons

Intermediate

interneurons

Roof plate

Floor plate

Dorsal root ganglion

Dorsal root

Lateral plate

(neuroepithelium, NEP cells)

Dorsal

neuroepithelium

Intermediate

neuroepithelium

Intermediate

neuroepithelium

Receding ventral

neuroepithelium

Receding ventral

neuroepithelium

Sojourn zone

of premigratory

neurons destined

for the dorsal horn

and intermediate

gray

Sojourn zone

of premigratory

neurons destined

for the dorsal horn

and intermediate

gray

Dorsal

root

Lateral cervical

nucleus?

Lateral cervical

nucleus?

axial

moto-

neurons

axial

moto-

neurons

Dorsal root

collateralization zone

Sulcus

limitans

Sulcus

limitans

Dorsal root

bifurcation zone

Dorsal funiculus

Expanding

gray matter

Expanding

white matter

Spinal canal with expanding

dorsal and receding ventral

components

Ventral

white commissure

Ventral

white commissure

Incipient

ventral median

fissure

V

e

nt

ral f

un

ic

u

l

u

s

V

e

nt

ral f

un

ic

u

l

u

s

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

proximal upper

limb motoneurons

proximal upper

limb motoneurons

distal

upper limb

motoneurons

distal

upper limb

motoneurons

Large arrows extending from the neuroepithelium indicate migrating neurons.
Small arrows in the spinal canal indicate the direction of expansion or contraction.

PLATE 10B