The Human Brain During the Third Trimester

Medial accessory olive

Medial accessory oliv e

Raphe nuclear complexRaphe nuclear complex

Reticular formation

Reticular fo rmation

Reticular formation

Reticular fo rmation

Corticospinal tract (forming pyramid)

Pontocerebellar fiber s

(thin transve rse bundles)

Pontocerebellar fiber s (decussation)

PONSPONS MEDULLAMEDULLA

SPINAL CORD

Pontine gray

Choroid plexus

Ve ntral cochlear nucleus?

Spinocerebellar tracts

Middle cerebellar peduncle Spinocer ebellar tract s

Spinocer ebellar tract s Ve ntral white commissure

Spinocephalic (spinothalamic) tracts?

Ventral corticospinal tract

Intraspinal tracts (intermingled with the medial longitudinal Medial lemniscuMedial lemniscuss fasciculus and tectospinal tract)

PyramidPyramid

Medial longitudinal fasciculus? (an island of axons with reduced premyelinating glia)

Ar cuat

e

nucleu

s

Ar cuat

e

nucleu

s Pyramidal decussation

Pyramidal decussation

Inferior olive (principal nucleus)

Inferior olive (principal nucleus) Myelination gliosis (ventral funiculus)

Germinal and transitional

structures in italics

Germinal and transitional

structures in italics

Fourth ve ntricle (lateral recess, torn)

Raphe migration (penetrating the medullary arcuate nucleus)

PLATE 244B