front matter 1

VVentral funiculusentral funiculus

VVentral grayentral gray Central canalCentral canal

Intermediate grayIntermediate gray

Dorsal root

bifurcation zone

Superficial fasciculus cuneatus

Deep fasciculus cuneatus

No reactive glia

Myelination

Dense reactive glia

Sparse reactive glia

Deep fasciculus gracilis

Superficial fasciculus gracilis

Dorsal root

collateralization zone

Lissauer's tract

Lateral

funiculus

Lateral

funiculus

EpendymaEpendyma

Tectospinal tract?

Medial longitudinal fasciculus?

Vestibulospinal tract?

Dorsal grayDorsal gray

Ventral rootlets

(myelinated)

VVentral rootentral root

Dorsal funiculus

Examples of reactive glia densities
and myelination

Ventral

corticospinal

tract

Ventral

corticospinal

tract

Lateral

corticospinal tract

Lateral

corticospinal tract

Dorsal rootDorsal root

Myelinated proximal

axons of ventral horn

motoneurons

Myelinated proximal

axons of ventral horn

motoneurons

S p i n o c e r e b e l l a r t r a c t s

S p i n o c e r e b e l l a r t r a c t s

I n t r

a s

p

i

n

a

l

t

r

a

c

t

s

?

I n t r

a s

p

i

n

a

l

t

r

a

c

t

s

?

Sp

in

o

c

ep

h

a

li

c

t

r

a

c

t

s

Sp

in

o

c

ep

h

a

li

c

t

r

a

c

t

VVentral gray commissureentral gray commissure s

VVentral white commissureentral white commissure

Ventral median fissure

Dorsal median septum

Dorsal intermediate septum

See the matched cell body stained section in Plates 48A and B

The fi ne lines in the lateral and ventral funiculi segregate regions of differing densities of reactive glia, not the borders of fi ber tracts. These

lines may correspond to the borders of some fi ber tracts, such as the spinocerebellar and the lateral corticospinal tracts. Other lines run across

fi ber tracts, such as the dense region adjacent to the ventral and lateral part of the ventral horn that includes the central part of the intraspinal

tracts and the deep parts of the spinocephalic tracts. Many of the fi ber tracts in the ventral and lateral funiculi overlap and do not have distinct

borders. The spinotectal, spino-olivary, spinoreticular, and ventrolateral reticulospinal tracts (all unlabeled) intermingle with the spinocephalic

fi bers. The medial longitudinal fasciculus and tectospinal tract are interspersed with the medial fi bers of the intraspinal tracts; dorsal and lateral

fi bers of the intraspinal tract are infi ltrated by the lateral reticulospinal tract (unlabeled).

PLATE 47B