front matter 1

Sp

in

oc

ep

ha

li

c

tr

a

c

ts

Sp

in

oc

ep

ha

li

c

tr

a

c

ts

VVentral funiculusentral funiculus

VVentral grayentral gray

Lateral Intermediate grayIntermediate gray

funiculus

Lateral

funiculus

Vestibulospinal tract?

Dorsal grayDorsal gray

Dorsal root

bifurcation zone

Fasciculus gracilis

Dorsal root

collateralization zone

Lissauer's tract

Dorsal funiculus

Central canal

surrounded by ependyma

Central canal

surrounded by ependyma

Lateral

corticospinal tract

Lateral

corticospinal tract

Myelinated terminals of

dorsal root collaterals

Clarke's

column

Clarke's

column

Subgelatinosal pleSubgelatinosal plexusxus

Reticulated areaReticulated area

Ventral white

commissure

Ventral white

commissure

VVentral gray commissureentral gray commissure

Dorsal median septum

Ventral

median fissure

Rubrospinal tract?Rubrospinal tract?

Lateral

reticulospinal

tract?

Lateral

reticulospinal

tract?

Intraspinal trac

ts

?

Intraspinal trac

ts

?

The ventral commissure stains darkly in this section (the light area is a blood vessel). Apparently, all

axons in the commissure are myelinated. In contrast to rostral sections, all fi bers in the spinocephalic

tracts are darkly stained, indicating myelination is well on its way to completion at this level. The

external axons in the spinocephalic tracts at this level are more proximal to their cell bodies of origin

than at rostral levels, indicating a proximal (fi rst) to distal (second) gradient of myelination.

PLATE 100B

This Plate has no matched cell body stained section