Development Flashcards
Describe neural tube closure and the Neuroptera
It fuses from the middle along length in both directions. Defects in closure of the neuropores underlie serious and common birth defects of the NS
Pores = holes. Anterior = cranial, posteri
What are neural tube defects
Result from the failure of the rural tube to close
Failure can occur causally or cranial
Cranial defec results in ancephaly
Caudal defect results in spina bifida
What is spina bifida
Congenital defect where part of the spinal cord and meninges are exposed grout a gap in the spine
Can occur anywhere along the length, most commonly lumbosacral region
Neurological deficits occur, though not associated with cognitive delay
Hydrocephalus nearly always occur (Accumulation of fluid in ventricular system)
What are some ntds
Ancephaly - failure of nt closure cranially, absnce of central cranial structures including brain, incompatible with life
Rachischisis - failure of neural fold elevation
Decsribe the diagnosis and prevention of ntd
Raised maternal serum a-fetoprotein
USS
Multifactorial aetiology but Olin acid pre-conceptually and for the first trimester reduces incidence 70%
Describe the development of the spinal cord
Most of the length og the neural tube gives rise to the spinal cord.
At the 3rd month the spinal cord is the Sam length as the vertebral column
Thereafter the vertebral column grows faster
Spinal roots must elongate because they still exit at their intervertebral foramen
Forms the cauda equina
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Describe the initial evelopment of the brain (up to 4 weeks)
During neural old formation 3 primary brain regions can be distinguished
Forebrain - prosencephalon
Midbrain - mesencephalon
Hindbrain - rhombencephalon
After neural tube closure in the 4th week, these dilation at the cranial end become the 3 primary brain sickles
What are the secondary brain vesicles?
At 5 weeks o development 5 secondary brain vesicles are formed: telencephalon, diencephalon, mesencephalon, metencephalon, myencephalon
Five an overview of the mature derivatives of the ventricles
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What are the lectures?
Growth and development at cranial nt exceeds available space linearly so it must fold up
Cervical flexure - spinal cords-hindbrain junction
Cephalon flexure - midbrain region
Thus the neural axis does nto remain straight
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What results from the ventricular system
Tubular structure of he developing cns persists as development proceeds.
In the adult compressed of interconnected reservoirs filled by csf produced by cells of ventricular lining
Role: to fusion abrain and sc within the bone
Describe hydrocephalus
Most common in newborns suffering from spina bifida. Readily treatable by use o shunt. Can occur where there is any blockage of the ventricular system eg tumour, infection
Blocks natural low between chambers
Describe the early organisation of the neural tube
From inside out -
neuroepithelial layer
Intermediate (mantle) layer - neuroblasts
Marginal layer - processes
Roof and floor plates regulate dorsal and ventral patterning
Alar plate = sensory, basal plate = motor
What are neural crest cells
Cells of the lateral border of the neuroectoderm tube. Become displaced and enter the mesoderm and undergo epithelial to mesenchymal transition
What are dural crest derivatives
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