Eye and Ear Embryology Flashcards
4 sources that contribute to eye development
neuroectoderm of the brain (retina)
surface ectoderm of the head (lens)
mesoderm
NCC
when do optic grooves appear in cranial neural folds?
week 4
folds of optic grooves fold to form _______
optic vesicles
optic vesicles’ connections with forebrain thin to form _______ and induce overlying surface ectoderm to thicken, forming ________
optic stalks
lens placodes
lens placodes invaginate to form _______ which then fuse to form _______ and separate from surface ectoderm
lens pits
lens vesicles
optic vesicles invaginate for form _______
optic cups
why are meninges on the optic nerve?
because it is an outpouching of the forebrain
the retina develops from the ______
optic cup
outer layer of optic cup becomes
retinal pigment epithelium
inner layer of optic cup becomes
neuroepithelium of retina
neuroepithelium of retina contains
photoreceptor cells
what is a detached retina
when two layers of retina separate
two lens fibers
primary - from columnar cells
secondary - from cuboidal cells and along rim of lens
choroid, sclera, and ciliary body develop from
optic cup
what is the choroid
inner, vascular layer of mesenchyme
- extension forms ciliary body
what is the sclera
outer, fibrous layer of mesenchyme
iris develops from
rim of optic cup
muscles of iris (2)
dilator pupillae
sphincter pupillae
muscles of iris derived from
neuroectoderm of optic cup
cornea formation induced by
lens vesicle
3 sources of cornea
external corneal epithelium derived from surface ectoderm
mesenchyme continuous with developing sclera
NCC from optic cup
jelly-like substance that gives shape to eye found in posterior segment
vitreous humor
how do eyelids develop?
NCC proliferate and folds of skin grow over cornea
when do eyelids adhere together and when do they un-fuse
week 10
26+ weeks
failure of closure of the retinal fissure that may be inherited - leads to “keyhole” appearance of iris
Coloboma of iris
abnormal development of sclerus venous sinus caused by an imbalance between aqueous humor production and its outflow
congenital glaucoma
opaque lens
genetic
congenital cataracts
virus that can cross placental membrane and cause glaucoma and cataracts
rubella
dystrophy of levator palpebrae superior muscle
congenital ptosis of eyelid
small notch in eyelid devoid of eyelashes
coloboma of eyelid
external acoustic meatus develops from
1st pharyngeal groove
what is the meatal plug
cells of 1st pharyngeal groove form solid epithelial plate - this degenerates and becomes a cavity
mesenchyme proliferates from first and second arches to form
auricle
describe movement of auricle during development
initially in neck and is pushed superiorly by mandible development
middle ear develops from
tubotympanic recess from 1st pharyngeal arch
proximal part of tubutympanic recess forms _______
distal part forms _________
pharyngotympanic tube
tympanic cavity
development of internal ears (with arrows)
otic placodes –> otic pit –> otic vesicle
- dorsal region of otic vesicle –> endolymphatic duct, utricle, and semicircular
- ventral region of otic vesicle –> saccule and cochlear duct
earliest of 3 parts of ear to develop (happens in week 4)
internal ear
ventral saccular part of otic vesicle coils and grows to form ________
_______ differentiates from cells in wall of the cochlear duct
CN VIII cells migrate along coils to form ______ with cells that terminate on hair cells
membranous cochlea
spiral organ
spiral ganglion
