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