Neurodevelopment Part I Flashcards
When a fertilized egg undergoes cleavage as it is transported down the oviduct, it becomes what?
a blastocyst
A blastocyst implants in the uterine wall how many days after fertilization?
7 days
What is the layer of blastocyst called that becomes the embryo?
epiblast
The bilaminar disk is formed on what day?
day 13
What are the 3 germ layers of the bilaminar disk?
- Ectoderm
- Mesoderm
- Endoderm
Epiblast invagination occurs on day 13, which eventually forms the ____ on day 14.
primitive streak
The primitive streak gives rise to the _____ on day 14
primitive node
The hypoblast is replaced by _____ or lower layers on day 15
endoderm
The epiblast differentiates into _____ on day 15
ectoderm
On day 15, some epiblast cells differentiate into ____
mesoderm
On day 16, cells invaginate from the primitive node to form the what?
notochordal process
What structure is a tube of cells which eventually becomes a rod of cells?
notochordal process –> notochord
Neurulation is induction of the neural ____
plate
________ are signaling molecules secreted by neighboring cells. Some are ____, and some are attached to the cell surface. They bind to surface receptors on neighboring cells and activation of these receptors trigger the expression of _____ that code for intracellular proteins
inductive factors
diffusible
genes
What are the 3 intracellular proteins that can be coded by inductive factors in gene expression?
- Transcription factors
- Enzyme
- Cytoskeletal proteins
The _____ of a cell determines how it responds to inductive factors
competence
What differentiates into either the neural plate or epidermal cells?
ectoderm
What secretes BMP (bone morphogenetic protein)?
ectodermal cells
BMP prevents ____ from differentiating into neural cells
ectoderm
Induction of the neural plate occurs when a patch of nearby cells (“organizer region”) begins to secrete what?
BMP
Ectodermal cells close enough to the _____ to be exposed to BMP inhibitors differentiate into _____
organizer region
neural cells
BMP = ____dermal
epidermal
If BMP signaling is blocked, this causes ectodermal cells to differentiate into what?
neurons
What is the default fate for ectoderm?
neural phenotype
Intact + nothing = ____
Intact + BMP inhibitors = ____
Dissociated + nothing = ____
Dissociated + BMPs = ____
epidermal
neural
neural
epidermal
Transplanting a SECOND organizer produces what?
nearly complete second embryo
Anterior-posterior patterning begins in neural plate before formation of what?
the neural tube
A/p patterning depends on regional secretion of what inductive factor near the posterior end of the neural plate, and its inhibitors near the anterior end?
Wnt
Wnt inhibitors
The resulting Wnt concentration gradient causes anterior and posterior cells in the neural plate to express different what?
transcription factors
The different transcription factors regulate distinct sets of ____, leading to the differentiation of what 3 structures in the brain?
genes; forebrain, midbrain and hindbrain
Neural development is a chain reaction of inductive events turning _____ on and off in a precisely controlled ____ and ____ pattern
genes; spatial and temporal
Once the neural plate is induced, what forms down the midline?
the neural groove
The edges of the neural groove rise and fuse to form what?
the neural tube
Closure of the neural tube starts in the middle and proceeds to the anterior and posterior ends. Failure of neural tube closure can lead to what?
Neural tube defects
e.g., Spina Bifida, Anencephaly, Encephalocele
What structure is derived from the lateral margins of the neural tube?
the neural crest
When the neural tube fuses, the neural crest cells ____ and _____
internalize; migrate
Neural crest cells are precursors giving rise to the ____ and ____ (like Schwann cells) of the PNS, as well as the ____
neurons; glia
meninges
Neural Crest Derivatives Mnemonic: ACE PreSCHOOL
A = C = E = P = S = CH = O = ...O..= L =
Aortic arch
Connective/skeletal tissue of pharyngeal arches
Enterochromaffin cells of intestines
PNS Schwann Cells CHromaffin cells of adrenal medulla Odontoblasts melanOcytes Leptomeninges
What process converts a bilaminar structure consisting of epiblast and hypoblast into a 3-layer structure?
gastrulation
Changes in cell position, morphology and function are coordinated during development by what?
inductive factors and receptors
The competence of cells controls what?
how they respond to inductive factors
Induction of the neural plate is controlled by what? (2)
BMP and BMP inhibitors
What is the formation and closure of the neural tube called?
Neurulation
Anterior-posterior patterning of the neural tube involves induction of different transcription factors by ____ gradients
Wnt
The neural crest forms during ____ and gives rise to the neurons and glia of the ___ nervous system
neurulation; PNS
