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53 Cards in this Set

  • Front
  • Back
What is the Retina?
A specialized organ of the CNS
What does the Retina develop from?
An outpocketing of the diencephalon
What reciprocal interactions give rise to the eye development?
-Lens placode
-Optic vesicle
What is a Placode by definition?
A region of ectoderm that has regional identity - for instance the Lens placode, Otic placode, etc.
What is the Optic vesicle derived from?
Neural ectoderm
What is the lens placode derived from?
Surface ectoderm
How does the retina develop morphogenically?
By first the outpocketing, then an invagination.
What does the lens placode give rise to?
-Lens vesicle
What does the lens vesicle give rise to?
The lens
How do the layers of the developing retina differ from that of the cortex?
The ventricular (germinative) layer is NOT on the lumen side - a result of the weird morphogenesis.
What is similar about retinal neuroepithelial migration compared to cortical?
They both undergo interkinetic nuclear migration.
What type of cell capacity do neuroepithelial cells have?
What are the 2 layers of the Optic cup; what do they become?
1. Outer layer: pigmented epithelium
2. Inner layer: ventricular, intermediate, and marginal zones.
In what direction does cell proliferation and migration occur in the retina?
From Apical (back) to Lumenal (front) instead of the normal lumen->outside - because the ventricular zone is located away from the lumen.
What are the retinal precursor cells?
Multipotent neuroepithelium
How does neuroblast migration in the retina compare to cerebral and cerebellar cortex?
Both exhibit RADIAL migration but retinal migration is not guided by glial cells b/c they haven't developed yet.
Where do the first cells to become post-mitotic in the ventricular zone move?
To the basal-most layer.
What is the arrangement of the final layers of the retina?
Jumbled up - less stereotyped birth order.
What is important to remember about the retinal precursor cells? In Cerebellar?
Retinal: They are multipotent
Cerebellum: they are totipotent
What 2 cell types contribute to retinal development again?
1. Neural crest (moved away from neural tube)
2. Neuroepithelium (real stuff)
What contributes to the peripheral nervous system?
Same stuff:
-Neural crest
-Cranial Placodes
What are the 4 important features of the neural crest contributing to the PNS?
1. Have anterior to posterior specializations
2. There is a relationship between their time of migration and the type of derivative that will develop
3. They are stem cells
4. Migratory routes convey information about their fates
What exactly are neural crest cells?
Totipotent cells that delaminate from the neural tube and migrate away to form other structures.
What do neural crest cells have the capacity to do?
Be reimplanted in the neural tube and still form CNS structures
What 3 cell types do the neuroepithelial cells have the capacity to become?
1. Epithelial cells
2. Neural tube cells
3. Neural crest cells
What does it mean to say the peripheral nervous system has ant/post patterning?
Anterior develops first, then posterior.
What type of cell are neural crest cells?
Totipotent - really good examples of stem cells because they become so many various things.
Where do neural crest cells go when they delaminate and migrate away from the neural tube?
-Under scleratome
-Over myotome
In what order do neural crest cells mature?
Anterior first
Posterior last
At what area of the neural tube do crest cells delaminate?
The hinge region - these are multipotent cells; regionally fate, but if transplanted back into the CNS they would develop into neural cells.
Is it important whether neural crest cells migrate OVER or UNDER the myotome?
YES - the path of migration is very important in determining cell fate.
What is Slug?
A transcription factor that is expressed in an anterior to posterior fashion showing that's how neural crest cells mature.
Where would you find more fated cells, vs. higher potential cells in developing neural crest?
More fated: anterior

More capacity: posterior
What happens to neuroepithelial cells as they become neural crest?
Epithelial to mesenchymal transformation.
What are the 2 migratory pathways that Neural Crest cells can follow?
1. Dorsalateral
2. Ventromedial
-This is in reference to the myotomes
What do cells that follow the Dorsalateral pathway give rise to?
Ectodermal pigment cells
What do cells that follow the ventromedial pathway give rise to?
-Dorsal root ganglia
-Sympathetic chain ganglia
-Dorsal aorta
Where do neural crest cells migrate along somites?
What are Ephrins?
A family of guiding cepps - receptors and ligands that set up signaling cascades between somites and neural crest cells.
What is responsible for neural crest cells avoiding the caudal domain of somites?
Ephrin A4 receptor
How can neural crest be classified based on its Anterior-Posterior migration?
What is the importance of the A-P migratory positions of neural crest cells?
It determines the type of derivative that those cells will become.
5 Derivatives of Cranial neural crest cells:
-Smooth muscle
Derivative of Vagal/Lumbosacral neural crest cells:
Enteric nervous system
4 Derivatives of Trunk neural crest cells:
-Adrenochromaffin cells
What is the definition of a stem cell?
A cell that can give rise to an identical daughter stem cell (self-renew) or to one or more types of differentiated cells.
What is a pluripotent stem cell?
One that can give rise to TWO or more types of differentiated cells.
What is a placode?
An epidermal thickening that gives rise to specialized nervous system structures.
What are the placodes that develop? (5)
What is Hirschprung disease?
An enteric nervous system disease that is caused by defects in RET signaling.
What is RET?
A transmembrane receptor that binds RET ligands and is a Tyrosine Kinase signalling transducer.
How does variability in the degrees of patients suffering from Hirschprungs Disease arise?
From the complexity of the RET signalling pathway - different mutations can be classified.
What class of mutations is more severe?
Class 1 more severe than Class IV.