embryology of the eye Flashcards
2 germ layers important for formation of the eye
somatic mesoderm
ectoderm- neural tube
when do the ocular tissues form
begin in week 3
what is the embryonic structure that becomes the optic vesicle
diencephalon
first morphologic evidence of eye formation
presence of optic sulcus
optic vesicle connected to diencephalon by the
optic stalk
mesenchyme of optic formation includes what
neural crest cells + head mesoderm
optic cup is formed from what
optic vesicle
optic vesicle ventral invagination forms what
optic fissure/choroid fissue
choroid/optic fissure fuses when
early 5th-7th week
how does the optic cup close
dorsal to ventral direction
when optic cup closes what does it enclose
hyoid artery
ophthalmic artery
lens
how do the retina and RPE form in relation to each other
they have opposite orientations and remain as distinct layers
how do retinal progenitors differentiate and move
divide at the apical side of retina and then move to the basal side
how many neuronal cell types in retina
6
layers of cells in retina apical to basal
- rods and cones
- horizontal cells
- bipolar cells
- amacrine cells
- ganglion cells
Muller cells run the entire length
how many glial cells types in retina
1
photoreceptors
rods and cones
S-cones see what
short wavelengths- blue
M-cones see what
medium wavelengths- green
L-cones see what
long wavelengths- red
color blindness due to white
absence of one or more type of cone
when can the child begin to see color?
after the first few months
depression in retina forms- called what
macula
what is in the macula
fovea
what is special about fovea
light directly hits rods and cones- highest VA
when does fovea form
by month 7
vasculature of fovea
it is avascular
what does the fovea contain
only cones
what is the blind spot
the optic disk- where optic nerve inserts and no photoreceptors
what forms the iris stroma
neural crest and mesoderm
muscles of iris
dilator and sphincter pupillae
function of sphincter pupillae
constricts pupil- parasympathetic control
function of dilator pupillae
dilates pupil- sypathetic
where do the ciliary muscles come from
neural crest cells
what’d does the ciliary body consist of
pars plicata and pars plana
near vision activity of ciliary bodies
contracted
far vision activity of ciliary bodies
relaxed ciliary bodies
innervation of ciliary muscles
parasympathetic fibers
muscle responsible for near vision
circular muscle
muscle responsible for far vision
radial muscle
near vision lens
more convex
far vision lens
less convex
aqueous humor components
low protein concentration of plasma
trabecular meshwork derivative
neural crest
AH drains through what
Schlemms canal
Tm changes throughout life
loss of cells as we age
hyoid arteries surround what
lens to form the tunica vascutosa lentis (TVL)
what happens to lens during development
becomes avascular when TVL regresses
how do retinal arteries grow
from optic disk to the edge of retina
does the retina have lymph vessels
no
choriocapillaries supply what
RPE, photoreceptors and outer nuclear layers
vessels of photoreceptor layer and outer nuclear layer
avascular but supllied by choriocapillaries
veinous drainage of retina
vorticose veins
layers of inner eye
- inner to outer
retina
RPE
Choroid layer
sclera
sclera and choroid derivative
mesoderm
what’s the uvea
choroid, iris, ciliary bodies
necessary component of iris and retina formation
Pax6
what do zonular fibers connect to
lens capsule
solid part of vitrous
vitreous body
liquid part of vitreous
vitreous humor
what makes the vitreous humor
ciliary bodies
what does vitreous shrinkage lead to
floaters
when does pupillary membrane regress
between 6th and 8th weeks
layers of cornea
epithelium
Bowens layer
stroma
descemets membrane
endothelium
vessels fo cornea
it is avascular
when do eyelids reopen
by week 26
what forms the lacrimal glands
palpebral epithelium
chalazion is infection of the
meibomian gland
hordeulum is infection of
gland of zeis
space between lens and retina
vitreous chamber
space between lens and iris
posterior chamber
space between cornea and lens
anterior chamber
congenital cataracts
opacities of lens resulting from virus or mutations
persistent pupillary membrane is what
problem with pupillary membrane not regressing and it will cover pupil
coloboma
bilateralgap or defect in some structure of eye derived from slit in optic vesicle
cause of coloboma
failure of closure or fusion of embryonic optic fissure
histological changes in retina of glaucoma
atrophy of nerve fiber layer and ganglion cell layer
change seen in optic nerve of glaucoma
optic nerve cupping
bulgy eyes in children
bupthalmos
retinal detachment site of detachment
between RPE and outer segment layers of rods and cones
retinal detachment consequences
can lead to blinds due to lack of blood supply
retinopathy of prematurity
higher oxygen environemnt at birth than normal
- decrease in VegF
phase 1 of retinopathy of prematurity
vessel loss- low vegF
phase 2 of retinopathy of prematurity
vessel proliferation- neovascularization
anophthalmia
complete absence of ocular tissue due to failure of optic vessel formation
microphthalmia
small eyes associated with intrauterine infections from TORCH
aphakia
no lens
microphakia
small lens
retinal blastoma
retinal tumor that forms in eye in children under 5
- RB mutations and autosomal dominant
leukocoria
white pupil seen in retinoblastoma
what is the normal role of Rb
regulates the R point of the G1-S transition of cell cycle
