Early Development Lec02 Flashcards
Gastrulation defines the ___, ___, and ___ axes of the nembryo
midline, anterior-posterior and dorsal-ventral
the midline of the embryo is defined by the formation of the ____
notocord
notocord is formation incudes the formation of the ____
neural ectoderm
____ formationn is the ver y first event in neurogenesis
otochord formation
___ are the neural rpecurosr cells, which turns into CNS
neural ectoderm
if you treat ectoderm with ___ you get epidermis
bmp (a transforming growth factor beta)
if you treat ectoderm with ___ you get NEUROECTODERM
noggin chordin (inhibit BMP)
BMPs are made by the ____
surrounding tissue
Factors that inhibit BMP signaling are produced by the ____ (
notochord
___ signaling precedes BMP inhibition during neural induction
FGF
what do noggin and chordin do?
block bmp (thus, inducing neural development)
FGF stimulation increases production of ____
Noggin
neural induction the lateral margins of the____ fold inward to form the \n\nneural tube
neural plate
neural tube forms around day ___
20
the____ pinches off when the NEURAL TUBE is formed
neural crest
Neural tube closes from the middle both____ and ___
anteriorly and posteriorly (like a zipper going in both directions)
____ vitamins in the first few weeks of \n\npregnancy decrease neural tube closure defects.
B-complex (folic acid)
Spina Bifida rate in US is much lower since ____
nutrition
Spina Bifida is the failure of the ____ end of the neural tube to close
posterior
Anencephaly and holoprosenchephaly (Represents failure of the ___ neural tube to close.
anterior
Anencephaly and holoprosenchephaly lack ___
forebrain
____ makes cells in one area different from cells in another area
patterning
ventral patterning is realted to ___ function
motor
ventral siganl is secreted ____
sonic hedgehog
dorsal siganl is secreted ____
tgf betas
sonic hedgehog eventually leads to differences in ____
trnascription
What produces dorsal ventral polarity?
high sonic hedgehog in notocord and roof plate
no sonic headhog in the roof plate
roteins encoded by hox genes are powerful ____
transcriptional activators and repressors
results from abscence of sonic hedgehog:
- The forebrain does not form
- dorsal ventral polarity is disrupted
y dirsruptions in ____ also can cause cancers such as \n\nmedulloblastomas and basal cell carcinoma.
sonic hedgehog
Shh not only regulates polarity but ___
proliferation (disruptions in shh pathway can lead to different cancers)
cyclopy can be caused by abseence of ___
sonic hedge hog
when does anterior/posterior patterning occur? (relatively)
same time as neural induction and gastrulation (they all overlap)
spinal cord is from ___ patterning
anterior/posterior
rhomboencephalon is the future ___ and ___
pons and medulla
mesencephalon is the future ___
midbrain
diecepahlona nd telcephalon are part of the ____
prosencephalon
difference between fly and human hox genes\n
in humans they identify a specific segment along the anterior/posterior axis
Hox genes are involved in defining segmental differences in the ___, ___, and ___
spinal cord, \n\nmedulla and pons.
anterior/posterior patterning is accomplished through ___ genes
hox
there is no hox code for the ___ and ___
prosecenphalon and mesencephalon
OTX2 knockouts show complete loss of ____ polarity.
anterior
coordination of ___ and ___ regulates nervous system expansion
symmetrical and asymthetical proliferation
____ is needed to organize distinct cell types into functional units
cell migration
___ and ____s divide and differentiate in the ventricular zone
Neural stems cells and neural progenitor cell
multipotent stem cell either ___ or ___
neuronal or glial precurosr cells
___ increases the size of the ventricular zone, which in turn increases the size nof the brain.
symmetrical divisons
pluripotrnt neural stem cells are capable of ____
self renewal
As development proceeds NSCs begin to divide asymmetrically giving rise to
one neural stem cell and one neuro precursor
Late in development NSCs will again divide symmetrically but give rise to two
neural pecursors (and therefore NSC disappear)
number of NSCs, progenitors, neurons and glia needs to be tightly controlled as \n\ndoes the timing of their generatio by ___ and ___
notch and bhlh transcription factor
notch ____ proneural gene
deactivates
if you remove the inhibition of proneural gene by notch in the neural stem cell ____ is upregulated
delta
what happens at low/moderate levels of Notch stimulation through Delta?
, the intracellular domain of Notch is cleaved and goes to the nucleus to activate bHLH genes. (cell is eventually primed to diff into a neuron)
bHLH activation also ___ Delta on neural stem cells cells.
upregulates
Notch gets hyper-activated (by delta after it is upregulated)–>
shuts off proneuronal bHLH genes —-> keeping cell in pluripotent nsc state
In this case astrogliogenesis differentiation from neural progenitors is ___ \n\ndependent
Notch
astrogliogenesis differentiation from neural progenitors is inhbiited by ___
bhlh genes
oligodendrocyte generation is induce
by other factors (Oligs and Nkx 2.1) (factor other than nox)
neurogenesis is finished by the \n\nmiddle of the ____ trimester.
second
Timing of gliogensis happens mostly
after birth
The basic shape of the brain is fully formed at birth and the vast majority of the \n\n____ are already generated.
neurons
difference in brain after birth
dramatic increase in brain size, inc in myelin
primary neurlaiton is complete within the ___ weeks
first 3
most neurons in the cerebral cortex are produced between the ___ and ___ month of pregancy
first and 4th
f ectodermal pecursor cells are isolated and grown in a dish, they become ____
neurons (since there is no BMP present)
Stimulation of____ factors induce neural stem cell formation.
retinoic acid (RA), fibroblast growth factor (FGF) and insulin-like growth factor (IGF
what process are hox genes involved in?
posterior processing
how do hox genes create unique patterns of gene expression?
through repressing and enhancing each other
___ promotes astrogliogensis
notch
___ promotes oligodenrodensis
Olig1/2, Nkx 2.1
___ inhibits Oligodendrogenesis
BHLH
___ inhbiits Astrogliogenesis:
BHLH
