OcAnat_Test3 Flashcards
Ectoderm, mesoderm, and endoderm come from?
Epiblast
What germ tissues do the eye parts develop from?
Ectoderm and Mesoderm
What happens in Week 4(day 22-28)
Optic sulcus
Optic vesicle, mesenchymal sheath begins
Mesenchymal sheath completes
Retinal disk, RPE, lens placode
Optic stalk, hyaloid vessels, primordia of EOM
What is induction
the influence that one developing structure has on another
What forms the retinal pigment epithelium?
Cells of the superotemporal wall of the optic vesicle.
The walls of the optic vesicle are continuous with what structure?
Neuroectoderm of the future brain
What is mesenchyme derived from?
Mesoderm (middle germ layer) Neural crest (originate from neuroectoderm) This is a descriptive term and does not imply an origin from any particular embryonic germ layer.
What is the retinal disk?
Distal face of the optic vesicle.
Disk-shaped thickening of the neural ectoderm.
Will become the neural retina.
What does lens placode formation coincide with?
Constriction of the optic vesicle which forms the optic stalk
What two things are related to each other at the end of week 4?
Vascularization and pigmentation
What days does week 5 consist of?
Days 29-35
What structures appear in week 5?
Invagination of retinal disk and lens placode
Optic cup forms, blood vessels enter the choroidal fissure
Lens vesicle pinched, corneal epithelium, primary vitreous, hyaloid vasculary
The optic vesicle turns into what structure?
The optic cup.
day 29-32; 5th week.
How do the blood vessels gain access to the optic cup?
Through the choroidal fissure.
How does the lens vesicle come about?
Through the pinching off of the lens placode from the surface ectoderm
During week 5, what structures does the hyaloid artery supply?
Lens vesicle
Developing retina
Is the choroidal fissure ventral or dorsal to the optic stalk?
It is on the ventral surface.
What is the purpose of the vasa hyaloidea propria
Supplying the vitreous chamber. Tiny branches of the hyaloid artery.
What blood network supplys the lens?
tunica vasculosa lentis.
Originates from the hyaloid artery.
What is so special about the lens when it is super grown?
It doesn’t need a blood supply.
Hyaloid artery degenerates
Hyaloid canal remains.
What does the proximal portion of the central retinal artery become?
Central retinal artery, which supplies the retina.
When does melanin appear in RPE?
Day 33.
What days are in week 6?
Days 36-42
What is the dominating factor in week 6?
The closure of the embryonic choroidal fissure.
Thick inner wall of optic cup becomes…
Thin outer wall of optic cup becomes…
- Neural retina
2. RPE
Where do the primary lens fibers come from?
Cells of the posterior wall of the lens vesicle. The elongation of these cells fills the cavity of the lens vesicle by the end of the 7th week.
Who forms the corneal epithelium?
The surface ectoderm after it separated from the lens vesicle.
Cells of basal layer of corneal epithelium are connected via….
Maculae adherens
Cells of the superficial layer of the corneal epithelium are connected via
Zonulae adherens
Zonulae occludens.
WHen do the secondary vitreous appear?
At the end of week 6. It pushes the primary vitreous inward towrd the lens and detach it from the sensory retina, except at periphery and optic disk area.
A lot of things happen in week six. GIve me a list
RPE Neural retina: outer nuclear zone, marginal zone Choroidal fissure closes Secondary vitreous appears Primary lens fibers appear Cornea epithelium appear
What are the honorable mention structures of week 6?
Eyelid
Nasolacrimal duct
Periocular vasculature
Orbital bones: Maxilla.
What does the first wave of mesenchyme cells form?
Corneal endothelium
Trabecular meshwork endothelium
What does the second wave of mesenchyme cells form?
Pupillary membrane, which is the primordium of the anterior border layer and stroma of the iris.
What is the purpose of the pupillary membrane?
Separates the anterior chamber from the posterior chamber
What does the third wave of mesenchyme cells form?
Primary corneal stroma - fibroblast
Secondary corneal stroma - keratocytes and collagen
The primary lens fibers become….
Embryonic nucleus
What two neuroblastic layers does the transient layer of CHievtiz separate?
Inner neuroblastic layer
Outer Neuroblastic layer
What happens to the mesencymal capsule during week 7?
Choroid and Sclera gets formed
CHoroid is homologous in origin with?
Pia mater
Arachnoid mater
Sclera is homologous in origin with?
Dura mater around the optic nerve and brain.
What happens to the optic stalk in the 8th week?
It becomes the optic nerve
Inner neuroblastic layer is differentiated into
Ganglion cells
Amacrine Cells
Mueller Cells
Another name for INBL is marginal layer of HIS
The outer neuroblastic layer is differentiated into
Bipolar cells
Horizontal cells
Rods and COnes
What is the canal of cloquet
When secondary vitreous push its way anteriorly and laterally, crushing the primary vitreous and vasa hyaloidea propria centrally.
Clearly formed by 5th month.
What structures evolve from the ectoderm?
Surface ectoderm
Neuroectoderm
Neural crest
What structures are made out of the surface ectoderm?
Corneal epithelium Conjunctiva epithelium Lacrimal glands Crystalline lens Eyelid structures Epithelium lining the nasolacrimal system
When does the monolayer cells of cornea turn multilayered?
6 weeks. After that neural crest cells(mesenchyme) form the corneal endothelium at week 7.
What happens at 7th week in the cornea?
COrneal epithelium is separated from the corneal endothelium by a diffuse basal lamina.
When does the descemet’s layer form?
When the endothelial cells are confluent
What happens after the endothelium is formed in the cornea?
Neural crest cells rub in b/w the endothelium and epithelium and turn primary stroma into secondary stroma
Where does the choroidal capillaries first appear?
At the posterior pole and then differentiate peripherally.
What is the order of appearance of choroidal circulation
Choriocapillaris forms first.
Next is short posterior ciliary arteries are added to supply choriocapillaris.
Long posterior ciliary arteries bypass the developing choroid.
Primary lens fibers appear in week 6 and week 7
6: transformation of the posterior cells of the lens vesicle into primary lens fibers
7: Filling of the cavity of primary lens fibers.
