Flashcards in Development of the Nervous System Deck (17):
The CNS devel from where?
What process produces the notochord?
What does the notochord produce?
Induces neurulation = conversion of overlying ectoderm to neurectoderm
Thickening and elevation of the neural plate = neural tube formation
By what day is the NT completely closed?
Process takes place in 10 days
Cranial neuropore closure defect can result in what?
Caudal neuropore closure defect can result in what?
Describe spina bifida
Defect in closure of neuropore
Most commonly a defect in caudal (lumbosacral) neural tube to close
Untreated hydrocephalus = cognitive delay
Can contain – CSF, meninges and neural tissue
Which neural tube defects are incompatible with life?
Anencephaly = failure of NT closure cranially, absence of cranial structure including brain
Rachischisis = failure of neural fold elevation
How are neural tube defect diagnosed?
Raised maternal serum alpha-fetoprotein
How can neural tube defects be prevented?
Pre-conceptual and 1st trimester reduces incidence by 70%
Briefly how does the nervous system devel from the neural tube?
Neuroectoderm tube has 3 sections
1) lumen forms ventricular system
2) 3 cranial dilations = 5 anatomical divisions of the brain
3) caudal tail spinal cord
Outline how the spinal cord forms
Most of the length of the neural tubes gives rise to the spinal cord
When the spinal cord is the same length as the vertebral column the spinal roots must elongate – forming cauda equina
Outline the development of the brain
During neural fold formation 3 primary brain regions form:
1) forebrain, 2) midbrain, 3) hindbrain
Theses become the primary brain vesicles
At 5 weeks of development five secondary brain vesicles are formed
Blockage of the ventricular system (tumour, infection)
Obstruct flow = accumulation of CSF
What are the flexures of the NT?
Growth and development at cranial NT exceeds available space linearly, it must fold up
How do the ventricles of the brain form?
Tubular structures of the CNS persist through development