L02: Development And Anomalies Of Development Of CNS Flashcards
Between which days does the first neurone become born in pre-natal period
22-26days
What does it mean if the first neurones are born in 22-26 days
Mother doesn’t realise she is pregnant at this stage (22-26days) so environmental factors can affect the embryo
Does a just born infant have a fully developed brain
No
At 12 months (post natal) what is the state of profileration
Majority of proliferation is complete but not all neurones are born.
It is only the majority.
Why is the first 3 years of postnatal period important
Neurone form circuits via synapses
At what age is the brain mature in gross structures
20 years
Does development of the brain continue after 20 years
Yes
What are the 3 layers of cells in gastrulation
Endoderm
Mesoderm
Ectoderm
What does the endoderm form in the neonate
Viscera
What does the mesoderm form in the neonate
Musculoskeletal system
What does the ectoderm form in the neonate
Nervous system
What are the 3 layers/regions of the ectoderm
Epidermis
Neural plate border
Neural plate
Why does one part of the ectoderm from the neural plate
Physical cell to cell interaction when cell surface protein in that area allow the neural plate to form
Extracellular secreted molecules that come from the mesoderm and notochord to induce the ectoderm to from the neural plate
What is neuralation
Physical changes that occur in the ectoderm
As a result of neuralation what structures are formed in the ectoderm
Neural grove of the neural plate
Neural folds of the neural plate border
After neuralation what happens to the neural folds
Neural folds fuse together to from the neural crest and neural tube
What does the neural tube form
The CNS i.e spinal cord and brain
What does the neural crest form
The cells bodies within the PNS
What can occur if there is a defective closure of the neural tube anteriorly
Anencephaly
What is anencephaly
A baby born with no or limited brain
What happens if there is a defect in the close of the neural tube posteriorly
Spina bifida
What are the causes of neural tube closure defects
- Problem of cell division that is dependent on folic acid
- gene defects that affect cell to cell interactions
What happens to the neural tube that form the brain
Has swellings that represent the forebrain, midbrain and hindbrain.
What determines cells if they are anterior or posterior
Anterior posterior patterning
What is anterior-posterior patterning
Signals that determine whether cells are anterior or posterior
What signals tell the cell they are anterior to the brain
Signals secreted on cell surface
Name an example of a cell surface signal that signals to anterior of brain
Dickkopt
What signalling molecule are the anterior signals dependent on
Retinoic acid
What is retinoic acid
A derivative of Vitamin A
If a pregnant women takes EXCESS vitamin A what can happens to the anterior signalling
Interfere with the anterior signalling
What is dorsal- ventral patterning
Signalling molecule which produce a protein in the ventral part of the developing brain to get cells to dorsal or ventral part
What does the motor neurone in the ventral brain form
Cranial nerves
What other neurones are found in the ventral brain
Dopaminergic neurones
Serotenergic neurones
What does the grey matter of the cortex contain
Cell bodies
What occurs in the grey matter of the cortex to organise neurones during development
1) proliferation
2) migration
3) differentiation
Where does proliferation occur
Ventricular zone
What does proliferation in the ventricular zone result in
New neurones being formed
What happens to the baby neurones in the ventricles after they have been produced
Migrated
For migration to occur what is required
A signal
What structure forms a scaffold for migrating cells in the developing cortex for cells in the ventricular zone
Radial glia
How far does the neurones migrate up the radial glia
Not far only just up the ventricular zone
What happens to the ventricular zone as time moves on
Produce more and more new neurones
How far does the next batch of new neurones travel up the radial glia
More far than the first batch of neurones
What is the process of forming the inside layer first and then the outer layer called
Inside out layering
What abnormalities can occur if migration doesn’t work properly
Cortical dysgenesis
What is cortical dysgenesis
Cortex not forming properly
When does differentiation occur
When the neurones reach their final destination
What causes transmitter and ion channels to the neurones during differentiation
Differential gene activation
How do axons extern and grow to correct targets
At the tip of the axon a specialised region known as the growth cone tastes its environment of chemoattractant and repellents so it finds its right way
What is fascilation
When axons grow in bundles
What does fascilation cause the production of
White matter tracts in the brain
After the axon has founds it right way via growth cones how does it form synapses
With a 2 way signalling process
What is a 2 way signalling process
When the pre-synaptic neurone and post-synaptic neurone interact with neutrophic factors
How can actual neurones be lost
Necrosis and apoptosis
Name an example of a dorsal ventral signalling molecule
Sonic hedgehog
Name an example of a cortical dysgenesis
Lissencephaly
What is lissencephaly
Smooth cortex
