How does the neural tube form:
Ectoderm thickens to form neural plate
Neural crests from from ectoderm
Crests meet forming a hollow tube underneath called the neural tube
How do the eyes begin to form from the neural tube?
The Diencephalic vesicle of the neural tube give off lateral projections called the optic vesicles.
The optic vesicles reach the surface ectoderm which thickens (a placode - thicker embryological area) to form the optic placodes.
How are the optic cups formed?
The Optic placode invaginates, in turn pushing the optic vesicle to invaginate (forming a two layered optic cup around the placode)
What happens to the optic placode?
After it invaginates it seperates from the surface ectoderm becoming the lens vesicle which sits in the optic cup
How do developing blood vessels reach the optic cup?
Through a fissure in its inferior wall called the choroid fissure.
What forms the choroid and sclera?
Mesenchyme around the optic cup
What happens if the choroid fissure fails to close before birth?
Part of your eye (e.g. Iris, optic disc or retina) has a key-hole shaped opening called a coloboma
What do the two layers of the optic cup form?
Inner layer forms the inner 9 retinal layers
Outer layer forms the 10th retinal layer
This leaves a potential space between the two that can fill with fluid if perforated and cause retinal detachment
What structures ultimately from surface ectoderm?
- Eyelids
- Conjunctiva
- Corneal Epithelium
What structures ultimately form from mesenchyme?
Choroid
Stroma of cornea
Sclera
Extraocular muscles
