From Cradle to Grave: Development, Ageing
and Disease
BBS2002
, Case 01 BBS2002
PRENATAL DEVELOPMENT OF THE NERVOUS SYSTEM
On about day 15 of development, a thickening containing a midline groove forms along the
midsagittal plane of the embryonic disc, which has now assumed an oval shape. This thickening,
called the primitive streak, elongates to occupy about half the length of the embryonic disc, and the
groove, called the primitive groove, becomes deeper and more defined. The cranial end of the
primitive streak is expanded into a structure called the primitive node. It contains a depression,
called the primitive pit, which is continuous caudally with the primitive groove. Formation of the
primitive streak heralds the beginning of gastrulation.
Gastrulation
During gastrulation(day 16 of development) epiblast cells move toward the primitive streak, enter
the primitive streak, and then migrate away from the primitive streak as individual cells. The
movement of cells through the primitive streak and into the interior of the embryo is called
ingression.
Neurulation:
1
,In week 3-4 the formation of the nervous system out of the ectoderm layers starts. There is a specific
group of migrating cells that migrates through the primitive pit and it stays in the midline of the
embryo. These cells are the so called notochord. The notochord induces the formation of the neural
plate by stimulating thickening of ectodermal cells. The central cells of the neural plate move
outwards forming the neural groove and neural folds. This will close and then the neural tube will be
formed as it closes. The lips of the neural tubes will give rise to the neural crests cells. The neural
tube will eventually form the central nervous system and the neural crests cells will form the
peripheral nervous system. The expanded cranial portions of the neural tube will give rise to the
brain. The presumptive brain is already visibly divided into three regions: the future forebrain,
midbrain, and hindbrain. The narrower caudal portion of the neural plate (continuous cranially with
the hindbrain) gives rise to the spinal cord.
2
, Ventricular system and brain structures development
The structures of the ventricular system are derived from the neural canal which is the centre of the
neural tube. A Part of the primitive neural tube will develop into the brainstem. The neural canal
dilates within the prosencephalon, leading to the formation of the lateral ventricles and
third ventricle. The cavity of the mesencephalon forms the cerebral aqueduct. The dilation of the
neural canal within the rhombencephalon forms the fourth ventricle
1. Forebrain: (Prosencephalon)
o Telencephalon (cerebrum).
o Diencephalon
2. Midbrian:
o Mesencephalon
3. Hindbrain: (rhombencephalon)
o Metencephalon
o Myelencephalon
4. Brainstem:
o Pons (metencephalon)
o Mesencephalon → The whole midbrain
o Medulla oblongata (myelencephalon)
3
and Disease
BBS2002
, Case 01 BBS2002
PRENATAL DEVELOPMENT OF THE NERVOUS SYSTEM
On about day 15 of development, a thickening containing a midline groove forms along the
midsagittal plane of the embryonic disc, which has now assumed an oval shape. This thickening,
called the primitive streak, elongates to occupy about half the length of the embryonic disc, and the
groove, called the primitive groove, becomes deeper and more defined. The cranial end of the
primitive streak is expanded into a structure called the primitive node. It contains a depression,
called the primitive pit, which is continuous caudally with the primitive groove. Formation of the
primitive streak heralds the beginning of gastrulation.
Gastrulation
During gastrulation(day 16 of development) epiblast cells move toward the primitive streak, enter
the primitive streak, and then migrate away from the primitive streak as individual cells. The
movement of cells through the primitive streak and into the interior of the embryo is called
ingression.
Neurulation:
1
,In week 3-4 the formation of the nervous system out of the ectoderm layers starts. There is a specific
group of migrating cells that migrates through the primitive pit and it stays in the midline of the
embryo. These cells are the so called notochord. The notochord induces the formation of the neural
plate by stimulating thickening of ectodermal cells. The central cells of the neural plate move
outwards forming the neural groove and neural folds. This will close and then the neural tube will be
formed as it closes. The lips of the neural tubes will give rise to the neural crests cells. The neural
tube will eventually form the central nervous system and the neural crests cells will form the
peripheral nervous system. The expanded cranial portions of the neural tube will give rise to the
brain. The presumptive brain is already visibly divided into three regions: the future forebrain,
midbrain, and hindbrain. The narrower caudal portion of the neural plate (continuous cranially with
the hindbrain) gives rise to the spinal cord.
2
, Ventricular system and brain structures development
The structures of the ventricular system are derived from the neural canal which is the centre of the
neural tube. A Part of the primitive neural tube will develop into the brainstem. The neural canal
dilates within the prosencephalon, leading to the formation of the lateral ventricles and
third ventricle. The cavity of the mesencephalon forms the cerebral aqueduct. The dilation of the
neural canal within the rhombencephalon forms the fourth ventricle
1. Forebrain: (Prosencephalon)
o Telencephalon (cerebrum).
o Diencephalon
2. Midbrian:
o Mesencephalon
3. Hindbrain: (rhombencephalon)
o Metencephalon
o Myelencephalon
4. Brainstem:
o Pons (metencephalon)
o Mesencephalon → The whole midbrain
o Medulla oblongata (myelencephalon)
3
