Ectoderm Fate

• Neural tube development• Building the brain• You can see a lot by looking! The eye• Epidermis development

Brief overview on Ectoderm fate

Neural Tube Development

• Primary and Secondary Neurulation.

• Primary Neurulation is Anterior portion of NT development, whereas posterior is secondary neurulation

Primary Neurulation

Neural Tube closure• Either single or multiple points of closure• A-P neuropores• Problems with closure

– Spina bifida– Anencephaly– craniorachischisis

Control of neural tube closure• Genetic factors:

– Pax3, Sonic hedgehog, and openbrain

• Environmental factors:– Cholesterol and Folate

Secondary Neurulation• Formation of Medullary cord

Brain Development: AV axis

Brain Development: DV axis

Vertebrate Eye

Eye Field formation• Otx gene expression is high

– BMP, wnt signaling low

• Pax6 master regulator

Too much of a good thing?

• Increase in Sonic hedgehog• Widespread decrease in Pax6

Retina differentiation• Most Ventral cells=Pax2; optic stalk• Dorsal cells= BMPs, Rx1• Rx1 regulates Pax6 and Six3

Retina differentiation• Fate of neuroblast

determined by translation, not transcription

• Photoacceptor genes regulated by Xotx5b

• Xotx2 and Xvsx1 specify bipolar neurons.

• All transcribed in retinal cells• Translation regulated by

miRNAs– miR129– miR155– miR214– miR222

Lens/Cornea differentiation

Epidermis: The other Ectoderm descendent

Development of Hair

Development of Hair

Development of Hair