Defects of Neural Developments Flashcards
neurulation=
the formation of the neural tube, driven by intrinsic and extrinsic factors
neurulation begins
anteriorly, moves posteriorly
secondary neurulation=
de novo formation of the lumen
inititiation/neurulation of neural tube closure is best described as
discontinuous, as it is initiated in many areas which then merge
craniorachischisis=
middle part of the brain doesn’t close up (affects closure 10
ancephaly=
failure of neural closure in fore-mid-hind brain (affects closure 2)
spina bifida=
at posterior neuropore, at transition betweem lumen and solid mass so becomes exposed (affects closure 3)
the neural crest is a
transient and discrete embryonic population, natural stem cell pop.
the neural crest generate
neurons and glia of the PNS, pigment skin cells, cartilage in the head, DRG
describe the development of the DRG
develops from the neural crest, stops either side of the spinal cord and may require signals from the spinal cord.
what are the 3 kinds of sensory nuclei in the DRG?
nociceptors (trka), mechano and proprio ceptors (trkb and c)
TrkA=
receptor for neurotrophin (nerve growth factor)
TrkB=
neurotrophic tyrosine kinase receptor
TrkC=
NT-3 receptor
what mutation underlies CIPA?
TrkA mutation
CIPA-=
congenital insensitivity to pain with anhidrosis
what sensory neurons are affective by CIPA (and hence TrkA receptors) ?
nociceptors
what is neuroblastoma?
a tumour arising from the neural crest, of cells that will form the sympathetic nervous system
enteric system=
intrinsic NS of GI tract, which is populated with neural crest cells, from vagal and sacral levels of the neural tube
what does a mutation in Ret result in?
Hirschsprungs disease, which involves angliogenesis of the gut so no peristalsis
what is Ret?
transmembrane receptor tyrosine kinase
what happens in ret knockout mice?
lact enteric neurons, so no peristalsis and absence of myenterica and submucous plexuses
what does the death of precursors in ret knockout mice suggest about ret signalling?
that ret signalling is required for survival and diff. of precursors
what is the most common brain tumour in children?
medulloblasoma
medulloblastoma can arise fom
neuroepithelium or external granular layer (and can be developed from mutations in key developmental genes)
the external granular layer arises from
progenitor cells in the rhombic lip
progenitors in the ventricular zone give rise to
purkinje cells
what is the largest connective structur in the brain and how many axons does it have?
corpus callosum, 190 mill.
how does the corpus callosum develop?
from pioneer axons and signals from midline glial structures which help funnel the pioneer axons through
what is autism?
pervasive developmental disorder which affects language and social behaviour, there are a number of associated genes associated at synapses
what does agenisis of the CC cause?
autism like symptoms
what develpmental disorder does foetal alcohol syndrome have a 7% incidence of?
Ag CC
what are andermann syndrome, XLAG, mowat wilson syndrome, HSAS/MSASA and donnai-barrow syndome associated with?
AgCC
