L3 - neurodevelopment Flashcards
instructions for brain on assembling cells
genomic control
how are the different component of the brain organised and differentiated
transcription factors and morphogenes
how are components of the brain connected
neural circuitry
is the genome a conserved structure
yes
give an example of genetic divergence between species
dolphin and camel have very wrinkly cerebral cortex
squirrel and frog do not
gyrification
how wrinkly the cerebral cortex is
which organims is used to study neural development
and why is it useful
C. Elegans (worm)
small and simple - 302 neurons
allows complete tracking of cell developent
what technique is used to model neural tube formation
SEM
Scanning electron microscopy
process of neural tube formation
neural plate forma furrow at medial hinge point
neural groove forms as two sides converge
epidermis forms top layer
neural crest forms middle layer (peripheral NS)
neural tube bottom layer
what direction does neural tube formation occur in
from top to bottom
like a zip
what do dorso and ventral refer to in dorsoventral axis
dorso - sensory neurons
ventral - motor neurons
brainstem is divided into…
rhomberes
rhombere organisation
determined by Homeobox (Hox) gene expression
what is a rhombere
segment of developing neural tube
Timing and localization to the neural tube closure can lead to?
neural tube defects
e.g. anencephaly, spina bifida
where are cranial nerves restricted to?
specific rhomberes
Shh gradient
high Shh in ventral
low Shh in dorsal
increase in Shh concentration means….
increase in motor neurons
Shh is important for determining…
neural identity
what is produced by low Shh concentration
dorsal interneurons
ventral motorneurons require high Shh conc for
induction
progenitor domains
cell populations defined by combinations of transcription factors
transcription factors specify neuronal subtypes
within progenitor subtypes
what is a growth cone
specialist structure that guides neurones
axons grow towards
positive, attractive signals
axons grow by
polymerisation of cytoskeleton
what signals growth cones to targets
chemotactic or haptotactic stimulus
haptotactic stimulus
e.g. more adhesion sites
-ve cues
repel, cause downstream collapse of cytoskeleton
why is midline crossing important
relied upon by locomotion and sensory coordination
allows both sides of the NS to communicate
diagram for midline crossing
ladder diagram
longitudinal or crossed directions
neuromeres are the sections
Robo
transmembrane receptor
mutants cause growth in circles
continuous crossing of midline
Slit
chemorepellant ligand
mutants cause collapse of axon tracts down the midline
growth only down middle
neurophilin receptor and semaphorin ligand
essential for patterning peripheral nerves
factors that regulate complex development of cns
nerve growth factors
neurotrophic factors
how is neural plate formed
interaction of neural ectoderm with notochord
where does neural plate form furrow
medial hinge point
importance of HOX transcription factors
determine organisation between rostral and caudal axis
determine rhombomere organisation
what determines dorsoventral axis
shh
arguement against Shh dorsoventral hypothesis
studies on mice mutants for Shh lack ventral spinal cord characteristics
what relies of communication of both sides of the CNS
locomotion
sensory coordination
higher cognitive functioning
what is required for proper midline crossing
proper interaction between robo receptor and slit ligand
what is netrin
chemotropic signal secreted by floor plate
netrin deficient mice
do not form hippocampal commissure or corpus callosum
netrin-3
PNS
limited in CNS
