Neurodevelopment Part I

Question 1

When a fertilized egg undergoes cleavage as it is transported down the oviduct, it becomes what?

Answer 1

a blastocyst

Question 2

A blastocyst implants in the uterine wall how many days after fertilization?

Answer 2

7 days

Question 3

What is the layer of blastocyst called that becomes the embryo?

Answer 3

epiblast

Question 4

The bilaminar disk is formed on what day?

Answer 4

day 13

Question 5

What are the 3 germ layers of the bilaminar disk?

Answer 5

1. Ectoderm
2. Mesoderm
3. Endoderm

Question 6

Epiblast invagination occurs on day 13, which eventually forms the ____ on day 14.

Answer 6

primitive streak

Question 7

The primitive streak gives rise to the _____ on day 14

Answer 7

primitive node

Question 8

The hypoblast is replaced by _____ or lower layers on day 15

Answer 8

endoderm

Question 9

The epiblast differentiates into _____ on day 15

Answer 9

ectoderm

Question 10

On day 15, some epiblast cells differentiate into ____

Answer 10

mesoderm

Question 11

On day 16, cells invaginate from the primitive node to form the what?

Answer 11

notochordal process

Question 12

What structure is a tube of cells which eventually becomes a rod of cells?

Answer 12

notochordal process –> notochord

Question 13

Neurulation is induction of the neural ____

Answer 13

plate

Question 14

________ 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

Answer 14

inductive factors
diffusible
genes

Question 15

What are the 3 intracellular proteins that can be coded by inductive factors in gene expression?

Answer 15

1. Transcription factors
2. Enzyme
3. Cytoskeletal proteins

Question 16

The _____ of a cell determines how it responds to inductive factors

Answer 16

competence

Question 17

What differentiates into either the neural plate or epidermal cells?

Answer 17

ectoderm

Question 18

What secretes BMP (bone morphogenetic protein)?

Answer 18

ectodermal cells

Question 19

BMP prevents ____ from differentiating into neural cells

Answer 19

ectoderm

Question 20

Induction of the neural plate occurs when a patch of nearby cells (“organizer region”) begins to secrete what?

Answer 20

BMP

Question 21

Ectodermal cells close enough to the _____ to be exposed to BMP inhibitors differentiate into _____

Answer 21

organizer region

neural cells

Question 22

BMP = ____dermal

Answer 22

epidermal

Question 23

If BMP signaling is blocked, this causes ectodermal cells to differentiate into what?

Answer 23

neurons

Question 24

What is the default fate for ectoderm?

Answer 24

neural phenotype

Question 25

Intact + nothing = ____ Intact + BMP inhibitors = ____ Dissociated + nothing = ____ Dissociated + BMPs = ____

Answer 25

epidermal neural neural epidermal

Question 26

Transplanting a SECOND organizer produces what?

Answer 26

nearly complete second embryo

Question 27

Anterior-posterior patterning begins in neural plate before formation of what?

Answer 27

the neural tube

Question 28

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?

Answer 28

Wnt | Wnt inhibitors

Question 29

The resulting Wnt concentration gradient causes anterior and posterior cells in the neural plate to express different what?

Answer 29

transcription factors

Question 30

The different transcription factors regulate distinct sets of ____, leading to the differentiation of what 3 structures in the brain?

Answer 30

genes; forebrain, midbrain and hindbrain

Question 31

Neural development is a chain reaction of inductive events turning _____ on and off in a precisely controlled ____ and ____ pattern

Answer 31

genes; spatial and temporal

Question 32

Once the neural plate is induced, what forms down the midline?

Answer 32

the neural groove

Question 33

The edges of the neural groove rise and fuse to form what?

Answer 33

the neural tube

Question 34

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?

Answer 34

Neural tube defects | e.g., Spina Bifida, Anencephaly, Encephalocele

Question 35

What structure is derived from the lateral margins of the neural tube?

Answer 35

the neural crest

Question 36

When the neural tube fuses, the neural crest cells ____ and _____

Answer 36

internalize; migrate

Question 37

Neural crest cells are precursors giving rise to the ____ and ____ (like Schwann cells) of the PNS, as well as the ____

Answer 37

neurons; glia | meninges

Question 38

Neural Crest Derivatives Mnemonic: ACE PreSCHOOL ``` A = C = E = P = S = CH = O = ...O..= L = ```

Answer 38

Aortic arch Connective/skeletal tissue of pharyngeal arches Enterochromaffin cells of intestines ``` PNS Schwann Cells CHromaffin cells of adrenal medulla Odontoblasts melanOcytes Leptomeninges ```

Question 39

What process converts a bilaminar structure consisting of epiblast and hypoblast into a 3-layer structure?

Answer 39

gastrulation

Question 40

Changes in cell position, morphology and function are coordinated during development by what?

Answer 40

inductive factors and receptors

Question 41

The competence of cells controls what?

Answer 41

how they respond to inductive factors

Question 42

Induction of the neural plate is controlled by what? (2)

Answer 42

BMP and BMP inhibitors

Question 43

What is the formation and closure of the neural tube called?

Answer 43

Neurulation

Question 44

Anterior-posterior patterning of the neural tube involves induction of different transcription factors by ____ gradients

Answer 44

Wnt

Question 45

The neural crest forms during ____ and gives rise to the neurons and glia of the ___ nervous system

Answer 45

neurulation; PNS