CNS Development Flashcards
What are the three periods of CNS development?
- Embryonic
- Foetal
- Postnatal
When does the embryonic period start and finish?
Conception to week 9
What 2 layers make up the embryo before gastrulation?
- Epiblast
- Hypoblast
What happens during gastrulation?
Cells migrate through the primitive steak to form 3 layers:
- Endoderm
- Mesoderm
- Ecotoderm
What does each germ layer give rise to?
Ectoderm = Skin, hairs, nails, neural tissue Mesoderm = Muscle, bone, cartilage, vascular system Endoderm = Gut and respiratory system
When does the neural tube begin to form?
Between days 20-27
What cells make up the neural plate?
Neural progenitor cells
How does the neural groove form?
The neural plate bends
What does the neural groove go on to form?
The neural tube
What cells line the neural tube?
Progenitor cells
What is the name given for the area that the progenitor cells line the neural tube?
The ventricular zone
The hallow neural tube gives rise to what system?
The ventricular system and the spinal cord
The anterior tube becomes the brain or the spinal cord?
The brain
The caudal tube becomes the brain or spinal cord?
The spinal cord
What determines neocortical cell function?
Concentration of signalling molecules
Give examples of signalling molecules
Emx2
Pax6
What are the concentrations of Emx2 and Pax6 at the front and back of the brain?
Pax6 = High concentration at the front Emx2 = High concentration at the back
Progenitor cells are induced by higher concentrations of which signalling molecule to differentiate into Visual neurones?
Emx2
Progenitor cells are induced by higher concentrations of which signalling molecule to differentiate into Motor neurones?
Pax6
When does the foetal period start and finish?
Week 9 to week 40/42
What is the term for smooth brain
Lissencephalic
What gives the brain is characteristic folded appearance?
Sulci and gyral pattern
When do primary, secondary and tertiary sulci develop?
Primary = 8-26 weeks Secondary = 30-35 weeks Tertiary = 36-postnatal
Once neurons reach their target cortical region, what ways of communication and transferring information do they develop?
- Axons
- Dendrites
What do oligodendrocyte progenitor cells form?
Myelin sheaths around axons
What is the most important factor in the adolescent phase>
The environment
Which hormones are important in brain maturation?
Gonadal hormones
Oestrogen makes girls more susceptible to what?
Stress
Monocular development is dependent of receiving stimuli - what happens if one eye does not receive stimuli?
Unstimulated eye column will shrink and not develop properly
What is anencephaly?
The neural tube does not close at the top
What is spina bifida?
Caudal tube does not close
What is holoprosencephaly?
Two hemispheres of the brain do not develop
What is demyelination
Damage to the myelin sheath
What is Hypomyelination?
Abnormally low level of myelination
What is dysmyelination?
Malformed and defective myelin sheath
Describe Pelizaeus Merzbacher Disease
Mutation in PLP1 gene which encodes for transmembrane protein (myelin protein in the CNS).
What are some signs of Pelizaeus Merzbacher Disease?
- Abnormal eye movements
- Cognitive impairment
- Severe spasticity
- Ataxia
