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68 Cards in this Set

  • Front
  • Back
What are the major structures of the eye?
What causes these major structures to form?
Inductive interactions
Initial primordium of eyes:
Outgrowth of Diencephalon: Optic Groove
4 Eye precursors:
-Surface ectoderm
-Neural ectoderm
-Neural crest mesenchyme
-Paraxial mesoderm
What signals the optic groove to form? What tissue does the optic groove (sulcus) derive from?
Prosencephalic signaling center - optic groove is from Neural Ectoderm
First step in forming the eye:
Optic groove expands and forms Optic Vesicle
How does the optic vesicle remain attached to brain?
Via Optic Stalk - it becomes the optic nerve
What happens to the optic vesicle?
Folds inward and forms a double layered Optic CUP
What will the Optic Cup become?
Retina - 2 layers:
What is the precursor of the optic groove?
Neural Ectoderm
How does the Optic Cup fold and what is the result?
Assymetrically - thus it leaves an inferior groove called the Choroid Fissure
What tissue precursor forms the OUTER layers of the eyeball?
Neural CREST - this mesenchyme surrounds the optic cup.
How does the Lens Placode develop? From what?
The Optic Vesicle INDUCES it to form when it contacts SURFACE ECTODERM
What does the Lens Placode become?
Lens Pit
What happens to the Lens Pit?
It forms a closed Lens Vesicle, and eventually differentiates into LENS.
What does the Lens Vesicle induce before it differentiates into lens?
By detaching from surface ectoderm, it causes Surface Ectoderm to thicken -> Corneal Placode
So what is induced by:
-Optic Vesicle?
-Lens Vesicle?
Dienceph = Optic Groove to form
Optic Ves= Lens Placode to form
Lens Ves = Corneal Placode to form
3 Eye development Abnormalities:
1. Anophthalmia
2. Cyclopia
3. Synophthalmia
Absence of eye structures
2 types of Anophthalmia:
-Primary: only eye; rare; structures around eye normal

-Secondry: Eye AND brain
What is
Cyclopia: 1 eye in 1 orbit

Synophtl: 2 eyes in 1 orbit
What are both cyclopia and synophthalmia associated with?
Midline facial anomalies
2 portions of the Retina:
Boundary between them:
Neural + Nonneural
Ora Serrata
What are the layers of the Optic Cup? What separates them?
Inner layer
Outer layer
-Intraretinal space
What does the Choroid Fissure function for?
An inlet for vascular precursors; it extends into the optic stalk and closes in 7th wk.
What does the Outer Layer of Optic Cup become?
Pigmented Epithelium (Retina/Iris)
What does the Inner Layer of Optic CUp become?
Everything else
-Nonpigmented Iis
-Ciliary body
-Iris muscles
What is the precursor tissue of the iris muscles?
Neural crest
What are the 3 initial layers of the Inner layer?
In which layers do neurons develop?
Ventricular - Rods/cones

Intermediate - others
When is full visual potential achieved?
By age 2 yrs
What causes Congenital Detachment of the Retina?
Failure of the intraretinal space to close.
What are the Non-Neural portions of the iris?
-Ciliary body
What layers of the optic cup form the ciliary processes?
What layer of the optic cup forms the Pigmented Iris?
What layer of the optic cup forms the Iris muscles and Ciliary muscle?
Neural crest cells infiltrate
What does the Optic Stalk become?
The optic nerve - connects to the brain.
Where does the blood supply to the retina form?
In the retinal (choroid) fissure
of the optic stalk.
What does the lens form from?
Lens placode - thickening of surface ectoderm
What causes congenital cataracts?
Inteference w/ lens development
-Increased PTH
What induces the lens to form again?
The optic vesicle.
What does the Lens vesicle induce to form?
The cornea
What tissue forms the Posterior epithelium and Stroma of Cornea?
Neural crest cells
What does the ectoderm covering the outside of eyeball and inside of eyelids form?
What does the Choroid Layer develop from?
Neural Crest mesenchyme that surrounds the optic cup
Important features of the Choroid:
-Continuous w/ Arachnoid/Pia
-Vascularized and Pigmented
What does the Sclera develop from?
Neural Crest mesenchyme surrounding the optic cup (same as the Choroid)
Important features of the Sclera:
-Continuous w/ Dura
-External to Choroid
So of the layers around the eyeball, which are from Neural Crest? From Surf. Ectoderm?
Neural Crest: Choroid/Sclera

Surf Ectoderm: Eyelids/Lacrimal apparatus
What are the extraocular muscles derived from?
Paraxial mesoderm - somitomeres 1-3, and 5
What 5 things in the eye are from Paraxial mesoderm?
-Extrinsic Ocular muscles
-Vascular endothelium
-Fluid draining spaces
-Orbital soft tissue (?)
-Vitreous body
What causes Congenital Glaucoma?
Abnormal devo of the fluid draining spaces of the eye
What are the fluid draining spaces of the eye?
-Vitreous body (primary supplied by hyaloid artery, 2ndry replaces it and is avascular)
-Aqueous chambers (provide for continuous fluid removal)
What 2 things supply the developing eye with blood?
-Hyaloid arterial system
-Choroid vessels (around the optic cup)
What is Persistent Pupillary Membrane?
When the Hyaloid artery doesn't degenerate before birth and leaves vessels in front of the lens.
What is a Coloboma?
A notch in one or more ocular structures - usually inferior part of iris in midline
What causes a Coloboma?
Failure of the Choroid fissure to completely close
What causes Congenital Ptosis?
Failure of the Levator Palpebrae to form - fairly common
What is Microphthalmos?
Reduction of the eyeball volume - can range from mild to severe
What is extremely Severe Microphthalmos called?
Clinical Anophthalmia
What is the cutoff point for whether Microphthalmos will result in eyeball deficiency beyond size?
Week 8 - if problem occurs after this, no visual problems; just a small eye. If before, there will be problems.
What is Cryptophthalmos?
Absence of eyelids and a hidden eyeball that is malformed.
3 things that form from Optic Cup Inner layer:
-Sensory retina
-Ciliary body (nonpigmented)
-Iris (nonpigmented)
3 Things that form from Optic Cup Outer Layer:
-Pigmented retina
-Ciliary body (pigmented part)
-Iris (pigmented part)
What does the Optic cup develop from?
Neural ectoderm
What does the Surface Ectoderm become?
-Lacrimal Gland
-Cornea (anterior epithelium)
-Conjunctiva Epithelium
What does the Neural Crest Mesenchyme surrounding the eyeball become?
-Sphincter/Dilator Pupillae Mm.
-Ciliary muscle
-Cornea - Stromal cells and Posterior epithelium
What does Mesoderm contribute to the eye?
-Extrinsic ocular muscles
-Vascular endothelium
-Vitreous body
-Fluid draining spaces
-Orbit soft tissues
-Iris stroma