What is the critical period?
week 4-7
but susceptible until birth
What are the three embryo sources of the eye?
- Neuroectoderm
- Surface ectoderm
- Mesoderm/NC (mainly NC)
The eye is an extension of what?
the brain (diencephalon)
The structure growing out from the brain is called what from the inside, and what form the outside?
- Optic sulcus
- Optic vesicle (forms optic cup)
- connected to brain via optic stalk
- optic fissure forms on the bottom (BV runs through)
*whole structure is hollow
What is the optic cup?
- comes from optic vesicle
- has an outer and inner layer due to invagination
- intraretinal space forms b/t layers
What gives rise to the Iris and Ciliary Body?
rims of optic cup
*Where the outer and inner layers of the optic cup are connected
What structures come neuroectoderm?
- Iris - epithelium, SMC
- Ciliary Body - epithelium
- Retina - neural, pigmented
What comes form the inner layer of the optic cup? outer layer?
- Neural
2. Pigmented
What are the only muscles to come form neuroectoderm?
dilator and constrictor pupallae M of the iris
Where does the stroma of the iris come from? ciliary muscle (SMC) of the ciliary body?
- NC
2. mesenchyme (NC/mesoderm)
How do we get separation of the pigmented and neural retina?
- they should fuse, but some pathologies they don’t (DS, marfains, trauma)
- get intraretinal space
What is/causes Aniridia?
- lack of iris tissue or complete absence of the iris
- Pax6 gene mutation
- Caused by: arrest development at rim of optic cup during 8th week
*associated with glaucoma, cataracts, eye abnormalities
What is the induction of the lens?
the optic cup touches the surface ectoderm —> lens placode –invaginates–> lens pit –migrates in and lose attachments with SE–>lens vesicle
*eventually lens will be surrounded by optic cup, and SE re-constitute to give you epi of cornea
Where do the lens and epithelium of the cornea come from?
surface ectoderm
What type of epithelium comprises anterior lens? primary? secondary?
- cuibodal cells
- columnar cells (elongate and become transparent)
- cuibodal cells
*all come from surface ectoderm
What causes congenital cataracts?
- Genetics
- Rubella Virus
- Radiation of mom
- Enzyme deficiency (congenital galactosemia; galactose from milk accumulates in blood and tissues)
*Lens is opaque; problem with only lens (only hazy in lens)
What is the sclera?
outer layer (whites of eyes) that is continuous with the dura and stroma of cornea -fibrous layer, and forms stroma of cornea
What does the stroma come from?
NC
What is the choroid?
- vascular layer b/t sclera and retina
- just like pia and arachnoid layers in brain
- itself is NC, but the BVs inside are mesoderm
What is the pupillary membrane?
- transient structure due to eye lids fusing shut; covers the lens
- part of sclera
Where is the anterior chamber between? posterior? vitreous?
- cornea and iris
- iris and lens
- lens and back of eye
What is congenital glaucoma?
- Elevated intraocular pressure
- Abnormal development of the drainage mans of aqueous humor (scleral venous sinus)
* NC problem - Causes: genetics (mutations in CYP1B1 gene), Rubella infection
*affects the whole eye (whole eye is hazy)
Where do extra-ocular muscles come from?
prechordal mesenchyme –> preotic metopes –> muscles
What does the Hyaloid A. due?
- branch of ophthalmic a.
- supplies inner layer of optic up, lens vesicle, mesenchyme in optic cup
- eventually becomes central retinal a. to supply retina
