Development of the Central Nervous System

Biomedic Dept.Medical School, Unisba

Origin of Nervous System

CNS-The brain and spinal cord ectoderm neural epithelium.

•Proliferation neural plate neural groove neural fold neural tube.

• Proliferation neural plate neural groove neural fold neural tube.

• Neural Tube CNS (Brain&spinal cord)

• Neural Crest PNS & ANS(Cranial, spinal, autonomic ganglia)

• The rest is neural crest .

Neuralation• Formation of the neural

plate and neural tube(22-23 days)region of the fourth to sixth pairs of somite

• Two third craniallyfuture brain

• One third caudally spinal cord

• Fusion of the neural folds neural canalrostral neuropore (cranial)&caudal neuropore(

1. Ektoderm2. Neural tube bagian

dorsal3. Neural tube4. Neural tube bagian

ventral5. Notochord

Gen-gen yang berperan dalam perkembangan neural tube

A Sensory NeuronB Viscero sensory

neuron/motoricC Motoric neuronGen PAX3/7 berperan

dalam perkembangan Alar plate

Gen PAX 6 berperan dalam perkembangan basal plate

Defisit dari gen ini menyebabkan Syndrome de Waardenburg

Development of The Spinal Cord

Development of The Spinal Cord

3 concentric zones:- Ependymal/ ventricularlayer (internal) nucleated , mitotic cells- Mantle/intermediate layer (middle) the cell bodies of neuron and

neuroglial cells- marginal layer (outer) fibrous mass, processes of nerve cells.

Development of the Spinal Ganglia

• Neural crest cellsSpinal ganglia

• Peripheral process(dendrit)pass the spinal n. to sensory endings

• Central processdorsal roots of spinal nerve

• Myelination of nerve fiber oligodendrocyte

Development of spinal meningens

Positional changes of the spinal cord:

• The vertebral column and duramater grow more rapidly than the spinal cordpositional spinal cord does not persist

• New born(terminate L2/L3)& Adult (inferior L1)

Congenital anomalies of spinal cord

Development of The Brain

1 Telencephalon2 Diencephalon3 Mesencephalon4 Cerebellum5 pons4+5 Metencephalon6 Myelencephalon(medulla oblongata)7 Spinal cordI ProsencephalonII MesencephalonIII RhombencephalonA Cerebral trunk

 

Development of brainFusion of the neural folds in the cranial region & closure of the

rostral neuropore form 3 primary brain vesiclesPrimitive brain straight three point of expansion:Forebrain,Midbrain&Hindbrain

fore brain (prosencephalon) mid brain (mesencephalon)

hind brain (rhombencephalon).

Fourth week :embryonic brain grows rapidly and bends ventrally with the head fold• Flexure : cephalic/mid brain,

cervical, pontine

MYELENCEPHALON-Most caudal part called medulla oblongata- neuroblast(alar plate) marginal zone gracili

nuclei medially& cuneate nuclei laterally-Continued into spinal cord.-Vascular mesenchymechoiroid plexure.

- Neuroblast(basal plate)medial tp lateral: general somatic efferent(hypoglosal nerve), special visceral efferent(innv. Muscle from pharyngeal arches), general visceral afferent(vagus & glossopharyngeal nerve)

- Neuroblast(alar plate)1. general visceral afferent(impulses from the viscera) 2. special visceral afferent(taste fibers)3.general somatic aff. (Impulses from the surface of the head) 4. special somatic aff(impulses from the ear)

METENCEPHALON-From isthmus to pontine flexure.-Dorsal: cerebellum-Ventral: pons

MESENCEPHALON-Least modified-Overshadowed by fore and hind brains

DIENCEPHALON.-Epithalamus,thalamus,hypothalamus.-Evagination epiphysis-The wall optic chiasm-Infundibulum hypophysis.

TELENCEPHALON-Paired cerebral hemisphere-Three functions corpus striatum, rhinencephalon and pallium.

Congenital anomalies of brainAnencephaly

(Meroencephaly)MicrocephalyHydrocephalus

CraniumDevelopment of cranium

• Cranium develops from mesenchyme around the developing brain.

• The cranium consists of:Neurocranium

Viscerocranium

Congenital anomalies of cranium

Cranium bifidumAcraniaHolo-acrania

VertebraeDevelopment of vertebralMesenchymal cells are found

in three main areas: around the notocord, surrounding the neural tube, and in the body wallCartilaginous StageBony stage

Notocord expands to form the gelatinous center of the intervertebral disc -- the nucleus pulposus

Congenital anomalies of vertebrae

• Rachischisis

• Spina Bifida

Alhamdulillah