early development of nervous system Flashcards
which “state” do BMPs push ectoderm towards?
the epidermal state
where are BMP inhibitors produced?
in the notochord
blocking BMP leads to what?
induces the cells to take on a neural fate (default pathway)
what is characteristic at 20 days?
neural tube formation
in which directions does the neural tube close?
from the mid line both anteriorly & posteriorly
what disorder does this statement describe?
“failure of the posterior end of the neural tube to close”
spina bifida
what disorder does this statement describe?
“failure of the anterior end of the neural tube to close”
anencephaly & holoprosenchephaly
what are the 4 things that the neural crest gives rise to?
- cranial neural crest
- trunk neural crest
- vagal & sacral neural crest
- cardiac neural crest
what does “patterning” do?
makes cells in one area different from cells in another area
what does sonic hedgehog secrete?
ventral signal motor
what does TGF betas secrete?
dorsal signal sensory
what can high or low Shh expression lead to?
dorsal-ventral polarity
what 4 things does Anterior/posterior patterning lead to?
- spinal cord
- rhombencephalon
- metencephalon: future pons
- myelencephalon: future medulla
- mesencephalon: future midbrain
- prosencephalon
- diencephalon: future thalamus & retina
- telencephalon: future forebrain
what is the role of HOX genes in the posterior CNS patterning?
involved in defining segmental differences in the spinal cord, medulla and pons
how do HOX genes work to make unique segments in the CNS?
work through encoding transcriptional activator and repressors that will turn on/off genes to create unique patterns of gene expression
anterior/posterior patterning in the CNS is largely accomplished by_______?
HOX genes
what happens if you knockout OTX2?
complete loss of anterior polarity
these embryos completely lack forebrain neural structures
where do neural cells proliferate & differentiate?
in the ventricular zone
what is the ventricular zone?
thin strip of cells surrounding the CSF filled ventricles
increasing the number of pluripotent neural stem cells does what to the ventricular zone thickness?lateral size?
the thickness stays relatively constant and the ventricular zone expands laterally
if a pluripotent neural stem cell divides asymmetrically, what two cells is it giving rise to?
another NSC and 1 neural precursor
in the cerebral cortex, which comes first; neurogenesis or gliogenesis?
neurogenesis comes first
which two transcription factors regulate neural cell differentiation?
notch and bHLH
which comes first; oligodenderogiosis or astrogliosis?
astrogliosis
what inhibits astrogliogenesis differentiation? what activates it?
notch dependent activation and bHLH genes inhibit it
in development, when is neurogenesis usually completed?
early in 2nd trimester
around week 19
when is gliogenesis complete?
well after birth! there is no myelination at birth and it continues to increase to about 20 years old
what does radial migration of neurons depend on?
radial glia
what is a main function of the radial glial?
they give rise to neurons & provide scaffolding on which they can migrate to their appropriate destination
describe what it means that the cortex forms in an inside to outside manner
the layers closest to the ventricular zone form first (early born) while the layers furthest away from the ventricular zone form last (layer born)
what occurs in a reelin mutation?
disrupts the inside-out layering and leads to a cortex that is inside out
