©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
CMMB 403 Final Exam Questions and
Answers 100% Solved
What are the origins of the optic vesicle and the lens? - ✔✔optic vesicle =
forebrain (neural ectoderm)
lens = surface epidermis --> placode
Describe the process of lens induction - ✔✔1. the optic vesicle (forebrain)
induces thickening of the surface epidermis (prospective lens placode)
2. the optic vesicle pinches in to form the optic cup and the lens invaginate
as well (lens placode comes into contact w/ the optic vesicle)
3. the optic cup forms two layers: neural retina and the pigmented retina
4. the lens pinches off
What is a placode? - ✔✔epithelial thickening of ectoderm that develops into
neurons or other parts of the sensory organs
What is the function of jervine? - ✔✔Its a SHH inhibitor, preventing the
repression of Pax6 at the midline, causing cyclopia
What is the function of Pax6? - ✔✔Eye development
,©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
Where is Shh expressed along the midline? - ✔✔- the prechordal plate
(floor plate of the neural tube) and the notochord
How does the signalling in Mexican cave-dwelling fish differ for eye
development? - ✔✔- they sent need to see because they live in caves
- so they have evolved to over express Shh and down regulated Pax6
everywhere = no eye development
What is the function of the Rx gene? - ✔✔retinal development --> functions
to maintain the expression of Pax6 (AMPLIFY PAX6)
Where do neural crest cells form? - ✔✔The entire length of the neural tube
How do neural crest cells migrate? When in development does migration
occur? - ✔✔They undergo an EMT
- migrate in the 4th week of development
What transcription factors are necessary to cause the release of E-cadherin
and allow the neural crest cells to undergo an EMT and migrate -
✔✔Snail/Slug --> neural crest cells lose E-cadherin and become
mesenchymal and can migrate through the body
,©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
What are the four main regions of neural crest and what do they form? -
✔✔1. Vagal/ Sacral: forms the parasympathetic neurons that innervate the
gut
2. trunk: forms the sensory neurons and dorsal root ganglia (and the
melanocytes)
3. cranial: forms the bones and cartilage of the face
4. cardiac: forms the outflow tracts of the heart
What chemotaxis elements are responsible for the migration of the
vagal/sacral neural crest cells into the gut? - ✔✔gut produces GDNF signal
which binds to the RET receptors on the neural crest cells -->
chemoattraction that drives the movement of neural crest cells into the gut
What causes Hirschprungs disease? - ✔✔mutation in GDNF or the RET
receptor to prevent chemoattraction driving the movement of neural crest
cells to the gut
- dont get proper peristalsis in the gut anymore
What are the two pathways that trunk neural crest cells can migrate down?
Which one forms what and which happens first? - ✔✔First - the ventral
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
pathway: neural crest cells migrate to the anterior sclerotome where they
either become the sympathetic ganglia or the dorsal root ganglia
Second - the more dorsolateral pathway: future melanocytes migrate
between the dermis and epidermis
Where are the cell bodies of the sensory neurons found? - ✔✔- found in
the dorsal root ganglia, not right in the central nervous system
What drives the migration of trunk neural crest through the anterior
sclerotome instead of the posterior? - ✔✔- the neural crest cells express
Eph receptors
- the posterior sclerotome expresses ephrins
- these repel eachother
What do the neural crest cells who stay in the anterior sclerotome become?
- ✔✔if they stay in the anterior sclerotome --> become more dorsal cell
types DRG
What do the neural crest cells who are repulsed and migrate out of the
anterior sclerotome become? - ✔✔cells that migrate out of the anterior
CMMB 403 Final Exam Questions and
Answers 100% Solved
What are the origins of the optic vesicle and the lens? - ✔✔optic vesicle =
forebrain (neural ectoderm)
lens = surface epidermis --> placode
Describe the process of lens induction - ✔✔1. the optic vesicle (forebrain)
induces thickening of the surface epidermis (prospective lens placode)
2. the optic vesicle pinches in to form the optic cup and the lens invaginate
as well (lens placode comes into contact w/ the optic vesicle)
3. the optic cup forms two layers: neural retina and the pigmented retina
4. the lens pinches off
What is a placode? - ✔✔epithelial thickening of ectoderm that develops into
neurons or other parts of the sensory organs
What is the function of jervine? - ✔✔Its a SHH inhibitor, preventing the
repression of Pax6 at the midline, causing cyclopia
What is the function of Pax6? - ✔✔Eye development
,©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
Where is Shh expressed along the midline? - ✔✔- the prechordal plate
(floor plate of the neural tube) and the notochord
How does the signalling in Mexican cave-dwelling fish differ for eye
development? - ✔✔- they sent need to see because they live in caves
- so they have evolved to over express Shh and down regulated Pax6
everywhere = no eye development
What is the function of the Rx gene? - ✔✔retinal development --> functions
to maintain the expression of Pax6 (AMPLIFY PAX6)
Where do neural crest cells form? - ✔✔The entire length of the neural tube
How do neural crest cells migrate? When in development does migration
occur? - ✔✔They undergo an EMT
- migrate in the 4th week of development
What transcription factors are necessary to cause the release of E-cadherin
and allow the neural crest cells to undergo an EMT and migrate -
✔✔Snail/Slug --> neural crest cells lose E-cadherin and become
mesenchymal and can migrate through the body
,©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
What are the four main regions of neural crest and what do they form? -
✔✔1. Vagal/ Sacral: forms the parasympathetic neurons that innervate the
gut
2. trunk: forms the sensory neurons and dorsal root ganglia (and the
melanocytes)
3. cranial: forms the bones and cartilage of the face
4. cardiac: forms the outflow tracts of the heart
What chemotaxis elements are responsible for the migration of the
vagal/sacral neural crest cells into the gut? - ✔✔gut produces GDNF signal
which binds to the RET receptors on the neural crest cells -->
chemoattraction that drives the movement of neural crest cells into the gut
What causes Hirschprungs disease? - ✔✔mutation in GDNF or the RET
receptor to prevent chemoattraction driving the movement of neural crest
cells to the gut
- dont get proper peristalsis in the gut anymore
What are the two pathways that trunk neural crest cells can migrate down?
Which one forms what and which happens first? - ✔✔First - the ventral
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
pathway: neural crest cells migrate to the anterior sclerotome where they
either become the sympathetic ganglia or the dorsal root ganglia
Second - the more dorsolateral pathway: future melanocytes migrate
between the dermis and epidermis
Where are the cell bodies of the sensory neurons found? - ✔✔- found in
the dorsal root ganglia, not right in the central nervous system
What drives the migration of trunk neural crest through the anterior
sclerotome instead of the posterior? - ✔✔- the neural crest cells express
Eph receptors
- the posterior sclerotome expresses ephrins
- these repel eachother
What do the neural crest cells who stay in the anterior sclerotome become?
- ✔✔if they stay in the anterior sclerotome --> become more dorsal cell
types DRG
What do the neural crest cells who are repulsed and migrate out of the
anterior sclerotome become? - ✔✔cells that migrate out of the anterior
