The document discusses the development of the nervous system from the ectoderm germ layer. It describes how the neural plate forms and folds to become the neural tube. The anterior and posterior ends of the neural tube close to form the brain and spinal cord. The neural crest cells go on to form the peripheral nervous system while the neural tube forms the central nervous system. It then details the subdivision and development of the forebrain, midbrain, and hindbrain regions of the embryonic brain.

2. DR SHABANA ALI

3.  Three primordial
tissues
 endoderm
 mesoderm
 ectoderm
 Which tissue does
nervous system
develop from?
 ectoderm
11/6/2015 3

4. appears at the beginning of the 3rd week as a
slipper-shaped plate of thickened ectoderm,
the neural plate.
Its lateral edges soon elevate to form neural
Folds.
11/6/2015 4

5. Neural
crest
11/6/2015 5

6.  The neural folds approach each other in the
midline,forming neural tube .
 begins in the cervical region and proceeds in
cephalic and caudal directions.
11/6/2015 6

7. Neural
crest
11/6/2015 7

8. Anterior
neural
pore
Posterior
neural
pore
11/6/2015 8
Closure of the cranial
neuropore occurs at the25th
day
Closure of the caudal
neuropore occurs at 27 day.

9. Anterior
neural
pore
Posterior
neural
pore
failure to close =
anencephaly
failure to close =
spina bifida
11/6/2015 9

10.  Neural crest becomes
peripheral nervous
system (PNS)
 Neural tube becomes
central nervous system
(CNS)
 Somites become spinal
vertebrae.
Somites
11/6/2015 10

11. Prosencephalon
or forebrain
Mesencephalon
or midbrain
Rhombencephalon
or hindbrain
11/6/2015 11

12. mesencephalon
metencephalon
myelencephalon
6 weeks4 weeks
11/6/2015 12

15. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 48.20

17.  THE TELENCEPHALON, which forms the
cerebral hemispheres.
 THE DIENCEPHALON, which forms the optic
cup and stalk,pituitary gland , thalamus,
hypothalamus, and epiphysis.

18.  The diencephalon, consist of a roof plate
and two alar plates but there are no floor
and basal plates

19.  a single layer of ependymal cells with
vascular mesenchyme give rise to the
choroid plexus of the third ventricle .
 The most caudal part of the roof plate
develops into the pineal body, or epiphysis.
 serves as a channel through which light and
darkness affect endocrine and behavioral
rhythms.

20.  lateral walls of the diencephalon.
 the hypothalamic sulcus, divides the plate
into a dorsal and a ventral region, the
thalamus and hypothalamus,
 As a result of proliferative activity, the
thalamus gradually projects into the lumen
of the diencephalon,forming the massa
intermedia, or interthalamic connexus.

23.  The telencephalon, the most rostral of the
brain vesicles, consists of
 two lateral outpocketings, the cerebral
hemispheres
 a median portion, the lamina terminales.

24.  The cavities of the hemispheres, the lateral
ventricles, communicate with the lumen of
the diencephalon through the
interventricular foramina of Monro

26.  arise at the beginning of the fifth week of
development as bilateral evaginations of the
lateral wall of the prosencephalon.
 By the middle of the second month the basal
part of the hemispheres begins to grow and
bulges, has a striated appearance and is
known as the corpus striatum .

27.  Near the diencephlon a single layer of ependymal
cells covered by vascular mesenchyme form the
choroid plexus.
 Immediately above the choroidal fissure, the
wall of the hemisphere thickens, forming the
hippocampus.

29.  With further expansion, the hemispheres
cover the lateral aspect of the diencephalon,
mesencephalon, and cephalic portion of the
metencephalon


30.  internal capsule divide nuclear mass of the
corpus striatum by axons passing to and from
the cortex of the hemisphere.
 At the same time, the medial wall of the
area between the frontal and temporal lobes
becomes depressed and is known as the
insula .

31.  During the final part of fetal life, the surface
of the cerebral hemispheres grows so rapidly
that a great many convolutions (gyri)
separated by fissures and sulci appear on
its surface

32.  Cortex Development.
 The cerebral cortex develops from the
pallium, which has two regions:
 (a) the paleopallium, or archipallium,
immediately lateral to the corpus striatum,
 (b) the neopallium,between the
hippocampus and the paleopallium

34.  a number of fiber bundles, cross the
midline, connect the right and left halves of
the hemispheres.
 The most important fiber bundles make use
of the lamina terminalis.

36.  anterior commissure.
 hippocampal commissure, or
 fornix commissure.
 corpus callosum.
 posterior and habenular commissures,
 the optic chiasma

37.  Holoprosencephaly
 Exencephaly
 Hydrocephalus
 Microcephaly

38. 1.Mylencephlon ----medulla oblangata
 Basal plate-------- three motor nuclei
 Alar plate----------three sensory nuclei
 Roof plate------ ---ependymal layer(choroid
plexus)
 Floor plate---------region of median sulcus
11/6/2015 38

39. Metencephlon -----cerebellum,pons .
 Basal plate----------three motor nuclei
 Marginal zone of basal plate---pons
 Alar plate-----------pontine nuclei,three
sensory nuclei
11/6/2015 39

40. Basal plate ; 2 groups of efferent nuclei
 Marginal layer- --------- crus cerebri
Alar plate---------------superior and inferior
colliculi
11/6/2015 40

41.  THE TELENCEPHALON, which forms the
cerebral hemispheres.
 THE DIENCEPHALON, which forms the optic
cup and stalk,pituitary gland , thalamus,
hypothalamus, and epiphysis.