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Flashcards in Development Of The Central Nervous System Deck (36)
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We are born with about 100 billion/million neurons.?

100 billion


Name the 3 stages of prenatal development and how long each takes.

1. Germinal ( 1st week + 2nd week)=2 weeks

2. Embryonic ( 3rd week to the 8th week)= 5 weeks

3. Fetal ( 9th week until birth)=


What happens during Germinal Period?

There's conception to implantation of gastrulation


Define conception/fertilization.

Is the joining of the sperm and egg in the fallopian tube to form a unique human being. With 46 chromosomes which provide the blueprint of the embryo's physical characteristics.


How long does fertilization take?

12-24 hours after ovulation


What is a zygote?

It is a fertilized egg.


What happens during the 1st week(7 days) of development (Germinal)?

Day 1: fertilization

Day 2: zygote forms blastomeres (when cell divides)

Day 3: morula (solid ball resulting from blastomeres)

Day 4: Late morula

Day 5: Blastocysts

Day 6: Blastocysts move towards uterine wall

Day 7: implantation in the uterine wall( partially embedded in the endometrial stroma)


What happens during the 2nd week of development(Germinal period)?

Day 8: The trophoblast differentiates into 2 layers

☆ Syncytiotrophoblast

☆ Cytiotrophoblast (cellular)


Define gastrulation.

Is the process by which an embrioblast(inner cell mass) becomes gastrula and 2 cell layers becomes 3 cell layers.


What happens during embryonic period of human development?

There is establishing of main organ system.


Which 3 basic germ layers are established by the end of the 3rd week?

1. Ectoderm
2. Mesoderm
3. Endoderm


Define neurulation.

Is the development of the nervous system from the ectoderm, where it gives rise to the neural plate that develops into neural tube, finally giving rise to the spinal cord and brain.


What happens on the 20th day to the 23th day during neurulation?

20th day: Ectoderm thickens to form neural plate

21 day: Neural plate folds inward onto itself forming a neural groove with neural folds on either sides.

23th day: Neural groove deepens and neural folds fuse together forming neural tube.


Name and define one birth defect due to abnormal closure of the neural tube. Hint: at the rostral end, anterior.

Anencephaly (no brain development)

☆congenital defective development of the brain, with absence of the bones of the cranial vault and absent or rudimentary cerebral and cerebellar hemispheres, brainstem, and basal ganglia.


Which end of the neural tube gives rise to the spinal cord?

Caudal end(posterior)


Define Neural Crest.

Are small groups of neural fold cells which migrate from between the surface of the ectoderm and neural tube.


Define spina bifida.

Congenital defect with incomplete closure of the vertebral column at the caudal end(posterior).


Neural tube surrounds the_______which forms the_________of the fully developed spinal cord.

Neural canal, central canal


The tube contains of_________,which differentiate into neurons forming__________.

Neuroblast, grey matter


The developing process from neuroblast grow out to form________of the spinal cord.

White matter


When the neuroblast divides it gives two plates:

1. Alar plates (posterior), which forms the dorsal horns of the spinal cord.

2. Basala plates (anterior), which forms the ventral horns of the spinal cord


At their interphase develops a small_____of visceral efferent neuron.

Lateral horn


Name all 8 derivatives of neural Crest. Hint: MAC DM SSS

1. Melanocytes
2. Adrenal medulla
3. Cranial nerve ganglia
4. Dermis of the face and neck
5. Meninges (forebrain)
6. Spinal dorsal root
7. Sensory neurons
8. Schwann cells


During the 4th week the anterior(cranial part) end of the neural tube becomes expanded to form 3_________.

Primary brain-vesicles


Name the 3 primary brain-vesicles.

1. The prosencephalon (forebrain)
2. The mesencephalon (midbrain)
3. The rhombencephalon (hindbrain)


During the 4-5th week of development what happens. Hint :five things happen.

The precursor of the 👀 and 👂's (the ocular and auditory vesicles) are evident.

The alimentary canal, from mouth to anus is formed, and connects to the yolks sac for nourishment.

The ends of the arms and legs are present.

A primary system for blood circulation is formed, and a rudimentary heart begins to beat.

The Cerebral hemispheres differentiate around the 5th week.


During the 5th-6th week of development 3 primary brain-vesicles differentiate into 5 secondary brain vesicles, which are?

1. Telencephalon
2. Diencephalon
3. Mesencephalon
4. Metencephalon
5. Myelencephalon


Give the adult brain structures formed by the secondary brain vesicles.

Tel- cerebrum: Cerebral hemispheres (cortex, white matter,basal nuclei) ; amygdala,hippocampus,basal ganglia.

Dien- thalamus, hypothalamus, epithalamus (pineal gland)

Mesen- brain stem: midbrain; tectum and tegmentum

Meten- brain stem: pons and cerebellum

Myelen- brain stem: medulla oblongata


During the end of the 6th week of development. What happens to the Cerebral hemispheres?

They have grown and now cover the diencephalon.
As the two hemispheres grow toward each other, they meet in the middle and continue with their growth downwards.


During the end of the 6th week of development. What happens to the Cerebral hemispheres?

They have grown and now cover the diencephalon.
As the two hemispheres grow toward each other, they meet in the middle and continue with their growth downwards.