Wk 4.1 Neurodevelopment Flashcards
What is Gastrulation?
Involves the movement of cells from the outer surface of the embryo to its inside.
What are three cell layers of the embryo?
-Endoderm – inner layer – gut, liver and lungs
-Mesoderm – middle layer – connective tissue, muscle and vascular system
-Ectoderm – outer layer – Central and peripheral nervous system, skin
What is neurulation?
The process by which the neural tube is formed.
What are the neural tube defects?
-Spina bifida cystica
-Myelomeningocele- type of SBC
- Meningocele
- When does Cell proliferation happen?
2.When does asymmetric division occur?
1.Embryonic Day 28-42 - cells are proliferating symmetrically
- After day 42 - asymmetric division occurs
What is the term for back-front and top-bottom
Back-front =Dorsoventral axis
Top-bottom=Rostrocaudal axis
What are the three stages of Rostrocaudal patterning?
-Wk4 Anterior is specialist into 3 distinct regions
-Wk6 Anterior specialised into 5 distinct regions
-Wk11 Cerebrum has grown more rapidly
1.When does neurulation happen?
2.What happens?
- Happens in week 4 post conception
- Ectoderm layer thickens and flattens making a neural plate , which arises within the ectoderm layer
What happens in the neurodevelopment of the neural plate?
- After separation of the neural plate from the rest of the laters the ends of the neural plate push up against each other forming a v like fold
-Folds completely make a neural tube due to fusion forming spinal cord and Brain
-Development progresses many proliferative area surrounding the ventricle middle, which undergoes asymmetrical division causing the neural stem cells or epithelia cells to regenerate many forms of itself making a bigger one
What happens in neurogenesis?
- Neurogenesis happens 8 wk- 20wk gestation
-Neural stem cells become mature neurons
What area is surrounds the ventricles?
-Ventricular zone
- Subventricular zone
What doe the norodonal secrete?
Growth factors
What does lack of folate cause?
No closing of the anterior and posterior causing neural defects
What are the three regions of the neural tube?
- Prosencephalon - Forebrain, (Cerebral Cortex)
-Mesencephalon - Midbrain (Basal Ganglia and Thalamus)
- Rhombencephalon - Hindbrain
(Brain stem and Cerebellum)
What is the migration?
-Newly born immature neuronal cells migrate along radial glia
-Migrate from ventricular layer up through cortex
-Creates a radial inside-out pattern of development
What are the two types of migration?
-Radial Migration – moving outwards – detach themselves.
-Tangential Migration – moving upwards
What doe the ventral and dorsal patterning do?
-Ventral: Sonic Hedgehog (Shh) – Motor neurons and ventral interneuron’s
-Dorsal: Bone Morphogenic Proteins (BMP’s) – Dorsal interneuron’s
1.What are morphogens?
2.How do they work?
1.Molecules set up opposing concentration gradients in neural tube
2.Differing concentrations of morphogens induce different types of cells
-Therefore cells close to roof and floor plates will be exposed to higher concentrations of morphogen and those further away will be exposed to lower concentrations
What is the function of Neurotrophins?
-Support the life of a neuron
-Prevents neurons from apoptosis during development
-Required for maintenance of adult neurons
What are the types if neutrophins
- Nerve Growth Factor (NGF) - peripheral neurons
- Brain derived Neurotrophic factor (BDNF) - Motor neurons
-Neurotrophin 3 and 4/5 (NT-3, NT-4/5) – Neuronal precursors
Do the neurons undergo apoptosis
yes
What is an example axonal outgrowth repulsing signals?
Steer growth cone away from target- Membrane-bound Semaphorin
