Eye Development Flashcards
1
Q
- What week do the eyes start to develop?
A
- Wk 4-8
2
Q
- What are the three embryonic sources that help form the eye?
A
- Neuroectoderm
- Surface Ectoderm
- Mesoderm/Neural Crest
3
Q
- What is the origin of the eye?
A
- Diencephalon
4
Q
- What artery travels through the optic fissure
A
- Hyaloid a
5
Q
- Neuroectoderm helps form what structures of the eye
A
- Iris
- Neural retina-inner layer of optic cup
- Pigmented retina- outer layer of optic cup
- Retina
- Epithelium-neuroectoderm
- SMC
- Ciliary body
- Epithelium
6
Q
- The rim of the optic cup helps form the _ and _
A
- Iris
- Ciliary Body
7
Q
- What muscles are the only muscles in the body that are coming from neuroectoderm?
A
- Dilator pupillae .
- Constrictor pupillae
8
Q
- The ciliary m is derived from which embryological germ layer
A
- Mesoderm and NCCs
9
Q
- Detachment of the Retina
A
- Separation of the pigmented and neural retina
- Can be congenital (Downs or Marfans)
- Can be d/t trauma to the orbit
10
Q
- Aniridia
A
- Lack of iris tissue
- Results from arrest of development at rim of the optic cup during week 9
- May be associated with:
- Glaucoma
- Cataracts
- Other Eye Abnormalities
- Pax 6 gene mutations (Also remember that this gene aids in the development of the cochlea)
11
Q
- How is the lens formed?
A
- Induced by optic cup touching surface ectoderm
- Leads to cell cell interactions that turn on a new set of genes in the surface ectoderm
- Lens placode forms
- Lens placode thickens and invaginated into the optic cup to form the lens pit
- Lens pit loses attachment with surface ectoderm to becomes lens vesicle
- Surface ectoderm left over becomes the epithelium of the cornea
12
Q
- What are the various parts of the lens and what type of epithelium are they made of
A
- Anterior lens epithelium-cuboidal epithelium
- Primary lens fibers-tall, columnar (becomne transparent as the nuclei degenerate)
- Secondary lens fibers-cuboidal
13
Q
- What forms the epithelium of the cornea
- What forms the stroma of the cornea
A
- Surface ectoderm remaining after lens pit detaches from it
- NCCs
14
Q
- Congenital Cataracts
A
- Lens . is opaque and frequently appears grayish white
- Causes:
- Genetics
-
Rubella
- Lens is esp vulnerable between 4-7 weeks
- Radiation
- Enzyme Deficiency
- Congenital galactosemia
- Appears 2-3 weeks after birth
- Galactose from milk accumulates in blood and tissues
- Congenital galactosemia
15
Q
- What structures do the mesenchyme/neural crest cells help form in the eye?
A
- Sclera
- Outer layer
- Fibrous
- Stroma of cornea
- Choroid
- Inner layer
- Vascular layer (mesoderm)
- Pupillary membrane (covers lens temporarily)
- Transient structure (Wk 26)
- Part of sclera
- Ciliary body
16
Q
- The anterior chamber of the eye is from the _ to _ and contains _ humor
- This is absorbed by the scleral venous sinus (which is made from what embryological germ layer)
A
- Cornea to iris, aqueous
- NCCs
17
Q
- The posterior chamber of the eye extends from the _ to _ and contains _ humor
- This humor is made by ciliary epithelium which is a derivative of what embryological germ layer?
A
Iris to retina
Neuroectoderm makes up ciliary epithelium
18
Q
- Congenital Glaucoma
A
- Elevated intraocular pressure
- Results from abnormal development of the drainage mechanism of the aqueous humor (scleral venous sinus)
- Causes:
- Genetics
- Mutations in CYP1B1
- Rubella infection
19
Q
- The extra-ocular muscles are derivatives of _
A
- Prechordal mesenchyme
20
Q
- Blood supply to the eye comes from what embryological germ layer
- What are the two main blood supplies to the eye and what areas do they supply?
- What arteries do they supply?
A
- Mesoderm
- Hyaloid a.
- Branch off of opthalmic a.
- Supplies inner . layer of optic cup, lens vesicle, mesenchyme in optic cup
- Becomes the central artery of the retina (distal portion will degenerate)
- Aq humor supplies lens after this degenerates
- Choroidal vessels-come from ciliary a.
- Develop during 15th week
21
Q
- What is shown in the following image?
A
- Persistence of the hyaloid a.
- Distal part should normally degenerate
- In most cases, the eye is microphthalamic
22
Q
- Optic nerve
- Two layers of neuroblasts contain _ and _
- Fibrous layer contains _
A
- Rods and cones, ganglion cells
- Axons forming the optic n.
23
Q
- What serves as the TEMPLATE for optic n but DOES NOT BECOME THE OPTIC N
A
- Optic stalk
24
Q
- How does the optic n form?
A
- Fibers grow thru inner part of optic stalk
- Cavity becomes obliterated
- Hyaloid artery incorporated
25
Q
- Papilledema
A
- Increased intracranial pressure-slows venous return from retina
- Leads to fluid accumulation in the optic disc
- Edema occurs b/c the retinal vessels are covered by the meninges and lie imn the extension of the subarachnoid space
26
Q
- Coloboma
A
- Results when : Optic fissure fails to close completely; leaving a gap in the eye structure
-
Causes:
- Environmental factors
- Autosomal dominant characteristic
27
Q
- The retina is derived from
A
- Neuroectoderm
28
Q
- The lens is derived from
A
- Surface ectoderm
29
Q
- The sclera is derived from
A
- Mesencyhme
30
Q
- The stroma of the cornea is derived from
A
- Mesenchyme
31
Q
- The epithelium of the cornea is derived from
A
- Surface ectoderm
32
Q
- The choroid is derived from
A
- Mesenchyme
33
Q
- The smooth muscle and pigmented epithelium of the iris comes from
A
- Neural ectoderm (optic cup)
34
Q
- The stroma of the iris comes from
A
- Mesenchyme
35
Q
- The epithelium of the ciliary body comes from
A
- neural ectoderm (optic cup)
36
Q
- The stroma, ciliary muscle of the ciliary body comes from
A
- Mesenchyme
