1: Development of the Nervous system Flashcards
What is the process called neurolation
It is the embryological formation of the neural tube
What is the neural tube?
The embryological precursor of the CNS
Explain the formation of the neural tube in early development
- Around Week three:
- Neral plate develops as part of the ectoderm
- Neural folds form from the neural plates, differentiation into neuroepithelium and neural crest cells starts to appear
- At around day 25 the neural folds fuse and form the neural tube (neuroepithelium on walls, Neural canal in the middle and neural crest cells attached)
What are the characteristics of the neuroepithelium?
How does it undergo further differentiation?
Neuroepithelium –> Will form CNS
- lines the inner walls of the neural tube
It will differentiate into
- Neuroblasts
- All neurones with cell bodies in CNS
- Glioblasts
- Astrocytes, Oligodendrocytes
- Ependymal cells
- Lining ventricles and central canal
What are the characteristics of the neural crest?
How does if further develop?
Will form the PNS
Will differentiate into
- sensory neurons of dorsal roote ganglia
- Postganglionic autonomic neurons
- Schwann cells
- Non-neural derivates e.g. melanocytes
Explain the proliferation and differentiation of the neuroepithelium and explain the formation of white and grey matter
- Neuropithelium proliferates at the inside of the neural walls
- cells bodys migrate from ependymal (inside) layer up to form grey matter
- Fibrous projections start to form white matter
Which factors drive neural development and ependymal differentiation?
It is driven by:
Signaling Molecules secreted by surrounding tissue that attrackts, repulses migration and axonal growth
Explain / Name the Layers of the neural tube
How does the developing brainstem look like?
What significance does this have in adulthood?
Developing brainstem is basically an “unclosed neural tube”
- explains the medial location of motor and lateral location of sensory devision in brainstem (would be ventral and dorsal in spinal chord)
- Ventricles start to separate
How does the brain look at approx. 4 weeks?
What are the embryological synonyms for fore, mid and hindbrain?
Forebrain
- prosencephalon
Midbrain
- Mesencephalon
Hindbrain
- Rhombencephalon
What changes between 4th and 5th week in brain development?
Pic: 4th Week right, 5th week left
- Differentiation of forebrain and formation of the telencephalon and diencephalon
- Differentiation of hindbrain and formation of pons and medually
How does the brain develop von Week 5 to Week 8?
In week eight
More sturctures are visible:
- the two cerebral hemispheres develop
- And the cerebellum develops
How are the three flexures in the developing neural tube called?
Descibe the changes to the neural tube from 4th to 8th Week in regards to the Flexures
They start to get more complicated, cervical flexure starts to flex further and give rise to the spinal chord
Explain the embryological development of the cerebral cortex
It happens in Telencephalon
- radial glia cells (type of astrocyte) form tracts –> neruons migrate up upon the tracts
- This gives rise to the 6-layered structure of the cortex
What kind of developmental disorders can occur in the development of the neural tube/ neural system?
What is cranioachischisis?
What is anencephaly?
- often also brain parts missing (e.g. cortex)
- –> fatal
What is encephalocele?
What is iniencephaly?
Developmental disorfer of the upper neural tube
What is spina bifta occulata?
What is a closed spinal dysrphism?
What is a meningocele?
Neural tube defect
What is Myelomeningocele?
