The Human Brain During the Third Trimester

PART IV:

GW37

HORIZONT AL

PART IV:

GW37

HORIZONT AL

This specimen is case number B-301-62 (Perinatal RPSL) in the

Yakovlev Collection. A male infant was stillborn after a premature sepa-

ration of the placenta. This brain is classified as a Normative Control

in the Yakovlev Collection (Haleem, 1990). It was cut in the horizontal

plane in 35-μm thick sections. Since there is no available photograph of

this brain before it was embedded and cut, a photograph of the lateral

view of another GW37 brain that Larroche published in 1967 (Figure 4)

is used to show gross anatomical features.

The approximate cutting plane of this brain is indicated in Figure 5

(facing page) with lines superimposed on the GW37 brain from the Lar-

roche (1967) series. The anterior part of each section (on the left in

all photographs) is slightly dorsal to the posterior part. In terms of

the medial-lateral plane of sectioning, the part of each section near the

bottom of the page shows structures cut slightly dorsal to those on the

other side of the midline. As in all other specimens, the sections chosen

for illustration are spaced closer together to show small structures in

the diencephalon, midbrain, pons, and medulla. Illustrated sections are

spaced farther apart when they contain only large brain structures, such

as the cerebral cortex, basal ganglia, and cerebellum. Photographs of

19 different Nissl-stained sections (Levels 1-19) are shown at low mag-

nification in Plates 65-80. The core of the brain and the cerebellum

are shown at high magnification in companion Plates 81AB-95AB for

Levels 3-19.

Figure 4. Lateral view of a GW37 brain with major structures in the cerebral hemispheres labeled (the same

as Figure 1 repeated here for convenience). (From the photographic series of J. C. Larroche (1967) Maturation

morphologique du système nerveux central: ses rapports avec le développement pondéral du foetus et son age

gestationnel. In: Regional Development of the Brain in Early Life, A. Minkowski (ed.), London: Blackwell, page

248.)

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