13. Eye Development Flashcards
When does the eye begin to develop?
Day 22: When optic grooves appear
Describe the three embryonic sources of the tissue of the eye.
- Neuroectoderm
- Surface ectoderm
- Mesoderm (Neural crest)
Describe the three embryonic sources of the tissue of the eye.
- Neuroectoderm
- SE
- Mesoderm/NCC
- retina (neural retina and pigmented retina)
- epithelium of iris
- smooth muscle cells of the iris
- Epithelium of ciliary body
- optic nerve
Describe the three embryonic sources of the tissue of the eye.
- Neuroectoderm
2. Surface ectoderm
- Mesoderm/NCC
- lens of the eye
- corneal epithelium
Describe the three embryonic sources of the tissue of the eye.
- Neuroectoderm
- Surface ectoderm
3. Mesoderm/NCC
NCC
- Choroid
- Sclera
- Corneal endothelium
- Stroma of iris
Mesoderm:
- CT and vascularature of eye
- Ciliary muscle
Describe the development of optic cup and lens
- Optic grooves appear in neural folds
- As neural folds fuse, optic vesicles protude in head mesenchyme and contact surface ectoderm.
- Distal end of optic vesicle constricts to form optic stalk, which connects to brain.
- Optic vesicles sends signals to surface ectoderm adjacent to the vesicles to thickens → form lens placode, primordia of the lens.
- As placode invaginates into surface ectoderm, lens pit forms.
- Edges of lens pit fuses -> forms lens vesicle, which then loses contact with surface ectoderm.
- Anterior wall of vesicle: makes the lens epithelium (cuboidal cells)
- Cells in posterior wall lengthen -> forming transparent cells called primary lens fibers
- Secondary lens fibers are added to external sides of primary lens fibers
- Optic vesicles invaginate to form the optic cup (double layered) connected to brain by optic stalks
- Optic cup → retina;
- Optic stalk → optic nerve
Now that we have the optic cup, what. happens?
- Retinal fissures develop on ventral surface of optic cups & along optic stalks
- Axons of ganglion cells pass directly into optic stalk → form optic nerve.
- Myelination occurs late fetal period & first postnatal year
What are the parts of the retina and what are they made out of
Made from the wall of the optic cup from neuroectoderm
- Neural retina (inner layer of optic cup)- neuroectoderm
- Pigmented retina (outer layer of optic cup) - neuroectoderm
Components of iris and where are they made from?
Made from rim of the optic cup.
- Iris epithelium: neuroectoderm
- Stroma of iris: NCC
- Smooth muscle cells of iris (dilator pupillae and sphincter pupillae ms) are made of NEUROECTODERM.
What are. the only muscles that do NOT come from mesoderm?
Smooth muscle cells of iris (dilator pupillae and sphincter pupillae ms) are made of NEUROECTODERM.
Components of ciliary body and where are they madefrom?
- Epithelium of ciliary body: neuroectoderm
- Ciliary muscle is from mesoderm
Retina develops from walls of optic cup & forms two layers. How do we separate the two layers?
Intraretinal space separates retinal layers. As the retinal layers fuse, space disappears.
YOUR LAYERS OF RETEINA SHOULD NORMALLY FUSE.
What is aniridia?
- Aniridia: Mutation in PAX6 gene that causes lack of iris tissue or complete absence of the iris d/t arrested development at rim of optic cup at 8th week.
- Assx with: glaucoma, cataracts, other.
As lens is being made, it will be surounded by what?
optic cup
Lens is made from what cells?
Surface ectoderm
What is epithelium of cornea made from?
stroma of cornea?
Epithelium of cornea: Surface ectoderm
Stroma of cornea: Neural crest