The Eye Flashcards
what are the 4 things that the eyes are derived fom
- neuroectoderm
- surface ectoderm
- mesoderm
- nerual crest cells
what does the retina, iris, and optic nerve ceom from
neuroectoderm
what does the lens of the eye and the corneal epithelium come from
surface ectoderm
what does the fibrous and vascular coats of the eye come from
mesoderm
what does the choroid, sclera, and corneal epithelium come from
nerual crest cells
when does the eye appear
day 22
optic vessels ( eye grooves from day 22) later come in contact with surface ectoderm and induce changes and finally form what?
lens placode
what does the optic vesicle become when it invaginate and forms the double wall
optic cup
what connects the forebrain to the optic vesicles
optic stalk
what is inside the renal fissure that develop on the ventral surface of the optic stalk
hyaloid vessels
what does the retina develop from
the walls of the optic cups ( outgrowth of forebrain)
what becomes the pigmented layer of the retina
the outer thin layer of the optic cup
what becomes the neural layer of the retina
the inner thicker layer of the optic cup
the posterior part of the retina differentiates into what
rods and cones
adjacent ot the rods and cons is the mantle layer which is photoreceptive layer what does it give rise too
- outer nuclear layer
- inner nuclear layer
- ganglion cell layer
what is in the optic stalk
- optic nerve
- optic chiasm
- optic tract
what is the optic nerve a tract of
diencephalon
when is the optic nerve myleniated
3 months of birth ( by oligodendroctyes)
what is not capable of regeneration after transection
optic nerve
what is completed after 10 weeks of light exposure
the optic nerve fibers
what does the most common eye anomalies result form
the abnormal closure of the retinal fissure
what is characterized by a local gap in the retina and is usually inferior to the optic disc, in most cases it is bilateral ( due to the defective closure of the retinal fissure)
Coloboma of the Retina
what is it called when there is a defect in the iris or the notch in the pupillary margin. this can involve only the iris or extend deeper into the cilliary body and retina
coloboma of the iris
what results from the failure of the retina to close during week 6 of development
coloboma of the iris
what kind of nose is usually present in children with cyclopia
proboscis ( tubular in the middle of the forehead)
what does cyclopia result from
severe suppression of the midline cerebral structures
what does holoprosencephaly refer too
when the midline of cerebral stuctures fuse (cyclops)
what is it when there is a very small eye or it can be a normal appearing rudimentary eye , the affected side of the face will be undeveloped and the orbit is small.
microphtalmia
what is severe micropthalmia a result from
arrested development of the eye before the optic vesicle has formed in weel 4
most cases of simple microphtalmia are caused by what
infectious agents like
- rubella
- toxoplasma ghondii
- herpes
what is it called when there is a congenital absence of the eye
anophtalmia
in anophtalmia what still forms even though the eyelids dont form
eyelids
what is it called when early in the 4th week there is a failure in the eye vesicle to form
primary anophtalmos
what is it when there is the development of the forebrain that is suppressed and therefore there is an absence of the eye or eyes
secondary anophtalmos